Add and Subtract Square Roots

Add and Subtract Like Square Roots

Think about adding like terms with variables as you do the next few examples. When you have like radicands, you just add or subtract the coefficients. When the radicands are not like, you cannot combine the terms.

Example

Try it.

Simplify: \(2\sqrt{2}-7\sqrt{2}\).

Solution

	\(2\sqrt{2}-7\sqrt{2}\)
Since the radicals are like, we subtract the coefficients.	\(-5\sqrt{2}\)

Example

Try it.

Simplify: \(3\sqrt{y}+4\sqrt{y}\).

Solution

	\(3\sqrt{y}+4\sqrt{y}\)
Since the radicals are like, we add the coefficients.	\(7\sqrt{y}\)

Example

Try it.

Simplify: \(4\sqrt{x}-2\sqrt{y}\).

Solution

	\(4\sqrt{x}-2\sqrt{y}\)
Since the radicals are not like, we cannot subtract them. We leave the expression as is.	\(4\sqrt{x}-2\sqrt{y}\)

Example

Try it.

Simplify: \(5\sqrt{13}+4\sqrt{13}+2\sqrt{13}\).

Solution

	\(5\sqrt{13}+4\sqrt{13}+2\sqrt{13}\)
Since the radicals are like, we add the coefficients.	\(11\sqrt{13}\)

Example

Try it.

Simplify: \(2\sqrt{6}-6\sqrt{6}+3\sqrt{3}\).

Solution

	\(2\sqrt{6}-6\sqrt{6}+3\sqrt{3}\)
Since the first two radicals are like, we subtract their coefficients.	\(-4\sqrt{6}+3\sqrt{3}\)

Example

Try it.

Simplify: \(2\sqrt{5n}-6\sqrt{5n}+4\sqrt{5n}\).

Solution

	\(2\sqrt{5n}-6\sqrt{5n}+4\sqrt{5n}\)
Since the radicals are like, we combine them.	\(0\sqrt{5n}\)
Simplify.	0

When radicals contain more than one variable, as long as all the variables and their exponents are identical, the radicals are like.

Example

Try it.

Simplify: \(\sqrt{3xy}+5\sqrt{3xy}-4\sqrt{3xy}\).

Solution

	\(\sqrt{3xy}+5\sqrt{3xy}-4\sqrt{3xy}\)
Since the radicals are like, we combine them.	\(2\sqrt{3xy}\)

Add and Subtract Square Roots that Need Simplification

Remember that we always simplify square roots by removing the largest perfect-square factor. Sometimes when we have to add or subtract square roots that do not appear to have like radicals, we find like radicals after simplifying the square roots.

Example

Try it.

Simplify: \(\sqrt{20}+3\sqrt{5}\).

Solution

	\(\sqrt{20}+3\sqrt{5}\)
Simplify the radicals, when possible.	\(\sqrt{4}\cdot \sqrt{5}+3\sqrt{5}\)
	\(2\sqrt{5}+3\sqrt{5}\)
Combine the like radicals.	\(5\sqrt{5}\)

Example

Try it.

Simplify: \(\sqrt{48}-\sqrt{75}\).

Solution

	\(\sqrt{48}-\sqrt{75}\)
Simplify the radicals.	\(\sqrt{16}\cdot \sqrt{3}-\sqrt{25}\cdot \sqrt{3}\)
	\(4\sqrt{3}-5\sqrt{3}\)
Combine the like radicals.	\(\text{-}\sqrt{3}\)

Just like we use the Associative Property of Multiplication to simplify \(5(3x)\) and get \(15x\), we can simplify \(5(3\sqrt{x})\) and get \(15\sqrt{x}\). We will use the Associative Property to do this in the next example.

Example

Try it.

Simplify: \(5\sqrt{18}-2\sqrt{8}\).

Solution

	\(5\sqrt{18}-2\sqrt{8}\)
Simplify the radicals.	\(5\cdot \sqrt{9}\cdot \sqrt{2}-2\cdot \sqrt{4}\cdot \sqrt{2}\)
	\(5\cdot 3\cdot \sqrt{2}-2\cdot 2\cdot \sqrt{2}\)
	\(15\sqrt{2}-4\sqrt{2}\)
Combine the like radicals.	\(11\sqrt{2}\)

Example

Try it.

Simplify: \(\frac{3}{4}\sqrt{192}-\frac{5}{6}\sqrt{108}\).

Solution

	\(\frac{3}{4}\sqrt{192}-\frac{5}{6}\sqrt{108}\)
Simplify the radicals.	\(\frac{3}{4}\sqrt{64}\cdot \sqrt{3}-\frac{5}{6}\sqrt{36}\cdot \sqrt{3}\)
	\(\frac{3}{4}\cdot 8\cdot \sqrt{3}-\frac{5}{6}\cdot 6\cdot \sqrt{3}\)
	\(6\sqrt{3}-5\sqrt{3}\)
Combine the like radicals.	\(\sqrt{3}\)

Example

Try it.

Simplify: \(\frac{2}{3}\sqrt{48}-\frac{3}{4}\sqrt{12}\).

Solution

	\(\frac{2}{3}\sqrt{48}-\frac{3}{4}\sqrt{12}\)
Simplify the radicals.	\(\frac{2}{3}\sqrt{16}\cdot \sqrt{3}-\frac{3}{4}\sqrt{4}\cdot \sqrt{3}\)
	\(\frac{2}{3}\cdot 4\cdot \sqrt{3}-\frac{3}{4}\cdot 2\cdot \sqrt{3}\)
	\(\frac{8}{3}\sqrt{3}-\frac{3}{2}\sqrt{3}\)
Find a common denominator to subtract the coefficients of the like radicals.	\(\frac{16}{6}\sqrt{3}-\frac{9}{6}\sqrt{3}\)
Simplify.	\(\frac{7}{6}\sqrt{3}\)

Condensed: the full section is in OpenStax Elementary Algebra 2e.

Key Concepts

• To add or subtract like square roots, add or subtract the coefficients and keep the like square root.
• Sometimes when we have to add or subtract square roots that do not appear to have like radicals, we find like radicals after simplifying the square roots.

Add and Subtract Square Roots

Add and Subtract Like Square Roots

In the following exercises, simplify.

Try it.

\(8\sqrt{2}-5\sqrt{2}\)

Solution

\(3\sqrt{2}\)

Try it.

\(7\sqrt{2}-3\sqrt{2}\)

Try it.

\(3\sqrt{5}+6\sqrt{5}\)

Solution

\(9\sqrt{5}\)

Try it.

\(4\sqrt{5}+8\sqrt{5}\)

Try it.

\(9\sqrt{7}-10\sqrt{7}\)

Solution

\(\text{-}\sqrt{7}\)

Try it.

\(11\sqrt{7}-12\sqrt{7}\)

Try it.

\(7\sqrt{y}+2\sqrt{y}\)

Solution

\(9\sqrt{y}\)

Try it.

\(9\sqrt{n}+3\sqrt{n}\)

Try it.

\(\sqrt{a}-4\sqrt{a}\)

Solution

\(-3\sqrt{a}\)

Try it.

\(\sqrt{b}-6\sqrt{b}\)

Try it.

\(5\sqrt{c}+2\sqrt{c}\)

Solution

\(7\sqrt{c}\)

Try it.

\(7\sqrt{d}+2\sqrt{d}\)

Try it.

\(8\sqrt{a}-2\sqrt{b}\)

Solution

\(8\sqrt{a}-2\sqrt{b}\)

Try it.

\(5\sqrt{c}-3\sqrt{d}\)

Try it.

\(5\sqrt{m}+\sqrt{n}\)

Solution

\(5\sqrt{m}+\sqrt{n}\)

Try it.

\(\sqrt{n}+3\sqrt{p}\)

Try it.

\(8\sqrt{7}+2\sqrt{7}+3\sqrt{7}\)

Solution

\(13\sqrt{7}\)

Try it.

\(6\sqrt{5}+3\sqrt{5}+\sqrt{5}\)

Try it.

\(3\sqrt{11}+2\sqrt{11}-8\sqrt{11}\)

Solution

\(-3\sqrt{11}\)

Try it.

\(2\sqrt{15}+5\sqrt{15}-9\sqrt{15}\)

Try it.

\(3\sqrt{3}-8\sqrt{3}+7\sqrt{5}\)

Solution

\(-5\sqrt{3}+7\sqrt{5}\)

Try it.

\(5\sqrt{7}-8\sqrt{7}+6\sqrt{3}\)

Try it.

\(6\sqrt{2}+2\sqrt{2}-3\sqrt{5}\)

Solution

\(8\sqrt{2}-3\sqrt{5}\)

Try it.

\(7\sqrt{5}+\sqrt{5}-8\sqrt{10}\)

Try it.

\(3\sqrt{2a}-4\sqrt{2a}+5\sqrt{2a}\)

Solution

\(4\sqrt{2a}\)

Try it.

\(\sqrt{11b}-5\sqrt{11b}+3\sqrt{11b}\)

Try it.

\(8\sqrt{3c}+2\sqrt{3c}-9\sqrt{3c}\)

Solution

\(\sqrt{3c}\)

Try it.

\(3\sqrt{5d}+8\sqrt{5d}-11\sqrt{5d}\)

Try it.

\(5\sqrt{3ab}+\sqrt{3ab}-2\sqrt{3ab}\)

Solution

\(4\sqrt{3ab}\)

Try it.

\(8\sqrt{11cd}+5\sqrt{11cd}-9\sqrt{11cd}\)

Try it.

\(2\sqrt{pq}-5\sqrt{pq}+4\sqrt{pq}\)

Solution

\(\sqrt{pq}\)

Try it.

\(11\sqrt{2rs}-9\sqrt{2rs}+3\sqrt{2rs}\)

Add and Subtract Square Roots that Need Simplification

In the following exercises, simplify.

Try it.

\(\sqrt{50}+4\sqrt{2}\)

Solution

\(9\sqrt{2}\)

Try it.

\(\sqrt{48}+2\sqrt{3}\)

Try it.

\(\sqrt{80}-3\sqrt{5}\)

Solution

\(\sqrt{5}\)

Try it.

\(\sqrt{28}-4\sqrt{7}\)

Try it.

\(\sqrt{27}-\sqrt{75}\)

Solution

\(-2\sqrt{3}\)

Try it.

\(\sqrt{72}-\sqrt{98}\)

Try it.

\(\sqrt{48}+\sqrt{27}\)

Solution

\(7\sqrt{3}\)

Try it.

\(\sqrt{45}+\sqrt{80}\)

Try it.

\(2\sqrt{50}-3\sqrt{72}\)

Solution

\(-8\sqrt{2}\)

Try it.

\(3\sqrt{98}-\sqrt{128}\)

Try it.

\(2\sqrt{12}+3\sqrt{48}\)

Solution

\(16\sqrt{3}\)

Try it.

\(4\sqrt{75}+2\sqrt{108}\)

Try it.

\(\frac{2}{3}\sqrt{72}+\frac{1}{5}\sqrt{50}\)

Solution

\(5\sqrt{2}\)

Try it.

\(\frac{2}{5}\sqrt{75}+\frac{3}{4}\sqrt{48}\)

Try it.

\(\frac{1}{2}\sqrt{20}-\frac{2}{3}\sqrt{45}\)

Solution

\(\text{-}\sqrt{5}\)

Try it.

\(\frac{2}{3}\sqrt{54}-\frac{3}{4}\sqrt{96}\)

Try it.

\(\frac{1}{6}\sqrt{27}-\frac{3}{8}\sqrt{48}\)

Solution

\(\text{-}\sqrt{3}\)

Try it.

\(\frac{1}{8}\sqrt{32}-\frac{1}{10}\sqrt{50}\)

Try it.

\(\frac{1}{4}\sqrt{98}-\frac{1}{3}\sqrt{128}\)

Solution

\(-\frac{11}{12}\sqrt{2}\)

Try it.

\(\frac{1}{3}\sqrt{24}+\frac{1}{4}\sqrt{54}\)

Try it.

\(\sqrt{72{a}^{5}}-\sqrt{50{a}^{5}}\)

Solution

\({a}^{2}\sqrt{2a}\)

Try it.

\(\sqrt{48{b}^{5}}-\sqrt{75{b}^{5}}\)

Try it.

\(\sqrt{80{c}^{7}}-\sqrt{20{c}^{7}}\)

Solution

\(2{c}^{3}\sqrt{5c}\)

Try it.

\(\sqrt{96{d}^{9}}-\sqrt{24{d}^{9}}\)

Try it.

\(9\sqrt{80{p}^{4}}-6\sqrt{98{p}^{4}}\)

Solution

\(36{p}^{2}\sqrt{5}-42{p}^{2}\sqrt{2}\)

Try it.

\(8\sqrt{72{q}^{6}}-3\sqrt{75{q}^{6}}\)

Try it.

\(2\sqrt{50{r}^{8}}+4\sqrt{54{r}^{8}}\)

Solution

\(10{r}^{4}\sqrt{2}+12{r}^{4}\sqrt{6}\)

Try it.

\(5\sqrt{27{s}^{6}}+2\sqrt{20{s}^{6}}\)

Try it.

\(3\sqrt{20{x}^{2}}-4\sqrt{45{x}^{2}}+5x\sqrt{80}\)

Solution

\(14x\sqrt{5}\)

Try it.

\(2\sqrt{28{x}^{2}}-\sqrt{63{x}^{2}}+6x\sqrt{7}\)

Try it.

\(3\sqrt{128{y}^{2}}+4y\sqrt{162}-8\sqrt{98{y}^{2}}\)

Solution

\(4y\sqrt{2}\)

Try it.

\(3\sqrt{75{y}^{2}}+8y\sqrt{48}-\sqrt{300{y}^{2}}\)

Mixed Practice

Try it.

\(2\sqrt{8}+6\sqrt{8}-5\sqrt{8}\)

Solution

\(6\sqrt{2}\)

Try it.

\(\frac{2}{3}\sqrt{27}+\frac{3}{4}\sqrt{48}\)

Try it.

\(\sqrt{175{k}^{4}}-\sqrt{63{k}^{4}}\)

Solution

\(2{k}^{2}\sqrt{7}\)

Try it.

\(\frac{5}{6}\sqrt{162}+\frac{3}{16}\sqrt{128}\)

Try it.

\(2\sqrt{363}-2\sqrt{300}\)

Solution

\(2\sqrt{3}\)

Try it.

\(\sqrt{150}+4\sqrt{6}\)

Try it.

\(9\sqrt{2}-8\sqrt{2}\)

Solution

\(\sqrt{2}\)

Try it.

\(5\sqrt{x}-8\sqrt{y}\)

Try it.

\(8\sqrt{13}-4\sqrt{13}-3\sqrt{13}\)

Solution

\(\sqrt{13}\)

Try it.

\(5\sqrt{12{c}^{4}}-3\sqrt{27{c}^{6}}\)

Try it.

\(\sqrt{80{a}^{5}}-\sqrt{45{a}^{5}}\)

Solution

\({a}^{2}\sqrt{5a}\)

Try it.

\(\frac{3}{5}\sqrt{75}-\frac{1}{4}\sqrt{48}\)

Try it.

\(21\sqrt{19}-2\sqrt{19}\)

Solution

\(19\sqrt{19}\)

Try it.

\(\sqrt{500}+\sqrt{405}\)

Try it.

\(\frac{5}{6}\sqrt{27}+\frac{5}{8}\sqrt{48}\)

Solution

\(5\sqrt{3}\)

Try it.

\(11\sqrt{11}-10\sqrt{11}\)

Try it.

\(\sqrt{75}-\sqrt{108}\)

Solution

\(\text{-}\sqrt{3}\)

Try it.

\(2\sqrt{98}-4\sqrt{72}\)

Try it.

\(4\sqrt{24{x}^{2}}-\sqrt{54{x}^{2}}+3x\sqrt{6}\)

Solution

\(8x\sqrt{6}\)

Try it.

\(8\sqrt{80{y}^{6}}-6\sqrt{48{y}^{6}}\)

Condensed: the full section is in OpenStax Elementary Algebra 2e.

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Reyndu hvert og eitt á pappír fyrst. Sýndu svarið til að athuga; staðfestar lausnir er hægt að opna í lausnarforritinu fyrir hvert skref.

1. Add: ⓐ \(3x+9x\) ⓑ \(5m+5n\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   ⓐ \(12x\) ⓑ \(5m+5n\)

2. Simplify: \(\sqrt{50{x}^{3}}\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   \(5x\sqrt{2x}\)

3. Simplify: \(2\sqrt{2}-7\sqrt{2}\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   	\(2\sqrt{2}-7\sqrt{2}\)
   Since the radicals are like, we subtract the coefficients.	\(-5\sqrt{2}\)

4. Simplify: \(8\sqrt{2}-9\sqrt{2}\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   \(\text{-}\sqrt{2}\)

5. Simplify: \(5\sqrt{3}-9\sqrt{3}\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   \(-4\sqrt{3}\)

6. Simplify: \(3\sqrt{y}+4\sqrt{y}\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   	\(3\sqrt{y}+4\sqrt{y}\)
   Since the radicals are like, we add the coefficients.	\(7\sqrt{y}\)

7. Simplify: \(2\sqrt{x}+7\sqrt{x}\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   \(9\sqrt{x}\)

8. Simplify: \(5\sqrt{u}+3\sqrt{u}\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   \(8\sqrt{u}\)

9. Simplify: \(4\sqrt{x}-2\sqrt{y}\).

   Vinna í gegnum það Vísbending

   Sýna svarið

   	\(4\sqrt{x}-2\sqrt{y}\)
   Since the radicals are not like, we cannot subtract them. We leave the expression as is.	\(4\sqrt{x}-2\sqrt{y}\)

10. Simplify: \(7\sqrt{p}-6\sqrt{q}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(7\sqrt{p}-6\sqrt{q}\)

11. Simplify: \(6\sqrt{a}-3\sqrt{b}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(6\sqrt{a}-3\sqrt{b}\)

12. Simplify: \(5\sqrt{13}+4\sqrt{13}+2\sqrt{13}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(5\sqrt{13}+4\sqrt{13}+2\sqrt{13}\)
    Since the radicals are like, we add the coefficients.	\(11\sqrt{13}\)

13. Simplify: \(4\sqrt{11}+2\sqrt{11}+3\sqrt{11}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(9\sqrt{11}\)

14. Simplify: \(6\sqrt{10}+2\sqrt{10}+3\sqrt{10}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(11\sqrt{10}\)

15. Simplify: \(2\sqrt{6}-6\sqrt{6}+3\sqrt{3}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(2\sqrt{6}-6\sqrt{6}+3\sqrt{3}\)
    Since the first two radicals are like, we subtract their coefficients.	\(-4\sqrt{6}+3\sqrt{3}\)

16. Simplify: \(5\sqrt{5}-4\sqrt{5}+2\sqrt{6}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(\sqrt{5}+2\sqrt{6}\)

17. Simplify: \(3\sqrt{7}-8\sqrt{7}+2\sqrt{5}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(-5\sqrt{7}+2\sqrt{5}\)

18. Simplify: \(2\sqrt{5n}-6\sqrt{5n}+4\sqrt{5n}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(2\sqrt{5n}-6\sqrt{5n}+4\sqrt{5n}\)
    Since the radicals are like, we combine them.	\(0\sqrt{5n}\)
    Simplify.	0

19. Simplify: \(\sqrt{7x}-7\sqrt{7x}+4\sqrt{7x}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(-2\sqrt{7x}\)

20. Simplify: \(4\sqrt{3y}-7\sqrt{3y}+2\sqrt{3y}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(\text{-}\sqrt{3y}\)

21. Simplify: \(\sqrt{3xy}+5\sqrt{3xy}-4\sqrt{3xy}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(\sqrt{3xy}+5\sqrt{3xy}-4\sqrt{3xy}\)
    Since the radicals are like, we combine them.	\(2\sqrt{3xy}\)

22. Simplify: \(\sqrt{5xy}+4\sqrt{5xy}-7\sqrt{5xy}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(-2\sqrt{5xy}\)

23. Simplify: \(3\sqrt{7mn}+\sqrt{7mn}-4\sqrt{7mn}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(0\)

24. Simplify: \(\sqrt{20}+3\sqrt{5}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(\sqrt{20}+3\sqrt{5}\)
    Simplify the radicals, when possible.	\(\sqrt{4}\cdot \sqrt{5}+3\sqrt{5}\)
    	\(2\sqrt{5}+3\sqrt{5}\)
    Combine the like radicals.	\(5\sqrt{5}\)

25. Simplify: \(\sqrt{18}+6\sqrt{2}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(9\sqrt{2}\)

26. Simplify: \(\sqrt{27}+4\sqrt{3}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(7\sqrt{3}\)

27. Simplify: \(\sqrt{48}-\sqrt{75}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(\sqrt{48}-\sqrt{75}\)
    Simplify the radicals.	\(\sqrt{16}\cdot \sqrt{3}-\sqrt{25}\cdot \sqrt{3}\)
    	\(4\sqrt{3}-5\sqrt{3}\)
    Combine the like radicals.	\(\text{-}\sqrt{3}\)

28. Simplify: \(\sqrt{32}-\sqrt{18}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(\sqrt{2}\)

29. Simplify: \(\sqrt{20}-\sqrt{45}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(\text{-}\sqrt{5}\)

30. Simplify: \(5\sqrt{18}-2\sqrt{8}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(5\sqrt{18}-2\sqrt{8}\)
    Simplify the radicals.	\(5\cdot \sqrt{9}\cdot \sqrt{2}-2\cdot \sqrt{4}\cdot \sqrt{2}\)
    	\(5\cdot 3\cdot \sqrt{2}-2\cdot 2\cdot \sqrt{2}\)
    	\(15\sqrt{2}-4\sqrt{2}\)
    Combine the like radicals.	\(11\sqrt{2}\)

31. Simplify: \(4\sqrt{27}-3\sqrt{12}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(6\sqrt{3}\)

32. Simplify: \(3\sqrt{20}-7\sqrt{45}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(-15\sqrt{5}\)

33. Simplify: \(\frac{3}{4}\sqrt{192}-\frac{5}{6}\sqrt{108}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(\frac{3}{4}\sqrt{192}-\frac{5}{6}\sqrt{108}\)
    Simplify the radicals.	\(\frac{3}{4}\sqrt{64}\cdot \sqrt{3}-\frac{5}{6}\sqrt{36}\cdot \sqrt{3}\)
    	\(\frac{3}{4}\cdot 8\cdot \sqrt{3}-\frac{5}{6}\cdot 6\cdot \sqrt{3}\)
    	\(6\sqrt{3}-5\sqrt{3}\)
    Combine the like radicals.	\(\sqrt{3}\)

34. Simplify: \(\frac{2}{3}\sqrt{108}-\frac{5}{7}\sqrt{147}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(\text{-}\sqrt{3}\)

35. Simplify: \(\frac{3}{5}\sqrt{200}-\frac{3}{4}\sqrt{128}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(0\)

36. Simplify: \(\frac{2}{3}\sqrt{48}-\frac{3}{4}\sqrt{12}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(\frac{2}{3}\sqrt{48}-\frac{3}{4}\sqrt{12}\)
    Simplify the radicals.	\(\frac{2}{3}\sqrt{16}\cdot \sqrt{3}-\frac{3}{4}\sqrt{4}\cdot \sqrt{3}\)
    	\(\frac{2}{3}\cdot 4\cdot \sqrt{3}-\frac{3}{4}\cdot 2\cdot \sqrt{3}\)
    	\(\frac{8}{3}\sqrt{3}-\frac{3}{2}\sqrt{3}\)
    Find a common denominator to subtract the coefficients of the like radicals.	\(\frac{16}{6}\sqrt{3}-\frac{9}{6}\sqrt{3}\)
    Simplify.	\(\frac{7}{6}\sqrt{3}\)

37. Simplify: \(\frac{2}{5}\sqrt{32}-\frac{1}{3}\sqrt{8}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(\frac{14}{15}\sqrt{2}\)

38. Simplify: \(\frac{1}{3}\sqrt{80}-\frac{1}{4}\sqrt{125}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(\frac{1}{12}\sqrt{5}\)

39. Simplify: \(\sqrt{18{n}^{5}}-\sqrt{32{n}^{5}}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    	\(\sqrt{18{n}^{5}}-\sqrt{32{n}^{5}}\)
    Simplify the radicals.	\(\sqrt{9{n}^{4}}\cdot \sqrt{2n}-\sqrt{16{n}^{4}}\cdot \sqrt{2n}\)
    	\(3{n}^{2}\sqrt{2n}-4{n}^{2}\sqrt{2n}\)
    Combine the like radicals.	\(\text{-}{n}^{2}\sqrt{2n}\)

40. Simplify: \(\sqrt{32{m}^{7}}-\sqrt{50{m}^{7}}\).

    Vinna í gegnum það Vísbending

    Sýna svarið

    \(\text{-}{m}^{3}\sqrt{2m}\)

Haltu eigin vinnu þinni

Ókeypis reikningur bætir við athugasemdum við hverja kennslustund, skrá yfir það sem þú hefur lokið, leyst vandamál á einum stað og kennari sem þú getur spurt um þessa síðu.Stærðfræðin sjálf er opin öllum, skráður inn eða ekki.

Skráðu þig inn Innskráning

Tákn notuð hér

Pikkaðu á hvaða tákn sem er fyrir fulla skilgreiningu, mynd og hvað hvert bréf í því merkir.

\sqrt{x}square root, n-th root
The non-negative number whose square (n-th power) is x.\pmplus or minus
Both signs at once: x = 3 ± 2 means 5 and 1.\neqnot equal
The two sides are different.\leqless/greater than or equal
Inequalities that allow equality; < and > exclude it.|x|absolute value / modulus
Distance from zero: |−3| = 3. For a complex number, distance from the origin.iimaginary unit
i² = −1.\log_b xlogarithm, natural log
The exponent b must be raised to for x; ln uses base e.\mathbb{N}number sets
Naturals, integers, rationals, reals, complex numbers.

Hvernig á að nota: Add and Subtract Square Roots

1. Add and subtract like square roots
2. Add and subtract square roots that need simplification
3. To add or subtract like square roots, add or subtract the coefficients and keep the like square root.
4. Sometimes when we have to add or subtract square roots that do not appear to have like radicals, we find like radicals after simplifying the square roots.

Spurningar sem fólk spyr

What does it mean to solve an equation?

To find every value of the unknown that makes both sides equal. Each step is an operation applied to both sides that keeps the solution set the same, until the unknown stands alone.

Why do I sometimes get two answers?

A quadratic can cross the axis twice, so it can have two solutions. A degree-n polynomial has up to n. The graph shows where each one comes from.

How do I know whether to factor or use the quadratic formula?

Try factoring for a few seconds: look for two numbers that multiply to a·c and add to b. If nothing obvious appears, the discriminant b² − 4ac tells you how many real roots there are, and the formula finds them without guessing.

Hlutar þessarar síðu eru aðlagað frá OpenStax Elementary Algebra 2e (CC BY-NC-SA 4.0). Þjappað og endurútskýrt hér; villur eru okkar. Vegna þess að upprunalega efni er leyfilegt til notkunar án viðskiptalegrar hagsmuna er þetta námskeið ókeypis, selur ekkert og er deilt undir sama leyfi.

Meira í Algebra

Linear equationsQuadratic equationsSystems of equationsInequalitiesFactoringExpandingSimplifying expressionsFunctions and graphsExponential and logarithmic equationsPolynomial equationsAbsolute value