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Distributive Property

Simplify expressions using the distributive property

Simplify Expressions Using the Distributive Property

Suppose three friends are going to the movies. They each need \(\text{\$9.25};\) that is, \(9\) dollars and \(1\) quarter. How much money do they need all together? You can think about the dollars separately from the quarters.

They need \(3\) times \(\text{\$9},\) so \(\text{\$27},\) and \(3\) times \(1\) quarter, so \(75\) cents. In total, they need \(\text{\$27.75}.\)

If you think about doing the math in this way, you are using the Distributive Property.

Back to our friends at the movies, we could show the math steps we take to find the total amount of money they need like this:

\[\begin{array}{lll} & 3(9.25) & \\ 3(9 & + & 0.25) \\ 3(9) & + & 3(0.25) \\ 27 & + & 0.75 \\ & 27.75 & \end{array}\]

In algebra, we use the Distributive Property to remove parentheses as we simplify expressions. For example, if we are asked to simplify the expression \(3(x+4),\) the order of operations says to work in the parentheses first. But we cannot add \(x\) and \(4,\) since they are not like terms. So we use the Distributive Property,

Example

Try it.

Simplify: \(3(x+4).\)

Solution
\(3(x+4)\)
Distribute.\(3\cdot x+3\cdot 4\)
Multiply.\(3x+12\)

Some students find it helpful to draw in arrows to remind them how to use the Distributive Property. Then the first step in would look like this:

Example

Try it.

Simplify: \(6(5y+1).\)

Solution
Distribute.
Multiply.

The distributive property can be used to simplify expressions that look slightly different from \(a(b+c).\) Here are two other forms.

Example

Try it.

Simplify: \(2(x-3).\)

Solution
Distribute.
Multiply.
Example

Try it.

Simplify: \(\frac{3}{4}(n+12).\)

Solution
Distribute.
Simplify.
Example

Try it.

Simplify: \(8(\frac{3}{8}x+\frac{1}{4}).\)

Solution
Distribute.
Multiply.
Example

Try it.

Simplify: \(100(0.3+0.25q).\)

Solution
Distribute.
Multiply.

Condensed: the full section is in OpenStax Prealgebra 2e.

Evaluate Expressions Using the Distributive Property

Some students need to be convinced that the Distributive Property always works.

In the examples below, we will practice evaluating some of the expressions from previous examples; in part ⓐ , we will evaluate the form with parentheses, and in part ⓑ we will evaluate the form we got after distributing. If we evaluate both expressions correctly, this will show that they are indeed equal.

Example

Try it.

When \(y=10\) evaluate: ⓐ \(\ 6(5y+1)\) ⓑ \(\ 6\cdot 5y+6\cdot 1.\)

Solution
ⓐ
\(6(5y+1)\)
Simplify in the parentheses.\(6(51)\)
Multiply.\(306\)
ⓑ
Simplify.
Add.

Notice, the answers are the same. When \(y=10,\)

\[6(5y+1)=6\cdot 5y+6\cdot 1.\]

Try it yourself for a different value of \(y.\)

Example

Try it.

When \(y=3,\) evaluate ⓐ \(\ -2(4y+1)\)ⓑ \(\ -2\cdot 4y+(-2)\cdot 1.\)

Solution
ⓐ
\(\ -2(4y+1)\)
Simplify in the parentheses.\(-2(13)\)
Multiply.\(-26\)
ⓑ
\(\ -2\cdot 4y+(-2)\cdot 1\)
Multiply.\(-24-2\)
Subtract.\(-26\)
The answers are the same. When \(y=3,\)\(-2(4y+1)=-8y-2\)
Example

Try it.

When \(y=35\) evaluate ⓐ \(\ \text{-}(y+5)\) and ⓑ \(\ \text{-}\text{y}-5\) to show that \(-(y+5)=\text{-}\text{y}-5.\)

Solution
ⓐ
\(\ \text{-}(y+5)\)
Add in the parentheses.\(-(40)\)
Simplify.\(-40\)
ⓑ
\(\ -y-5\)
Simplify.\(-40\)
The answers are the same when \(y=35,\) demonstrating that\(-(y+5)=\text{-}y-5\)

Distributive Property

Simplify Expressions Using the Distributive Property

In the following exercises, simplify using the distributive property.

Try it.

\(\frac{1}{2}(n+8)\)

Try it.

\(\frac{1}{3}(u+9)\)

Solution

\(\frac{1}{3}u+3\)

Try it.

\(\frac{1}{4}(3q+12)\)

Try it.

\(\frac{1}{5}(4m+20)\)

Solution

\(\frac{4}{5}m+4\)

Try it.

\(9(\frac{5}{9}y-\frac{1}{3})\)

Try it.

\(10(\frac{3}{10}x-\frac{2}{5})\)

Solution

3x − 4

Try it.

\(12(\frac{1}{4}+\frac{2}{3}r)\)

Try it.

\(12(\frac{1}{6}+\frac{3}{4}s)\)

Solution

2 + 9s

Try it.

\(-2(y+13)\)

Try it.

\(-3(a+11)\)

Solution

−3a − 33

Try it.

\(-7(4p+1)\)

Try it.

\(-9(9a+4)\)

Solution

−81a − 36

Try it.

\(-9(3a-7)\)

Try it.

\(-6(7x-8)\)

Solution

−42x + 48

Try it.

\(5+9(n-6)\)

Try it.

\(12+8(u-1)\)

Solution

8u + 4

Try it.

\(16-3(y+8)\)

Try it.

\(18-4(x+2)\)

Solution

−4x + 10

Try it.

\(4-11(3c-2)\)

Try it.

\(9-6(7n-5)\)

Solution

−42n + 39

Try it.

\(22-(a+3)\)

Try it.

\(-12-(u+10)\)

Try it.

\(-4-(c-10)\)

Solution

−c + 6

Try it.

\((5m-3)-(m+7)\)

Try it.

\((4y-1)-(y-2)\)

Solution

3y + 1

Try it.

\(5(2n+9)+12(n-3)\)

Try it.

\(9(5u+8)+2(u-6)\)

Solution

47u + 60

Try it.

\(9(8x-3)-(-2)\)

Try it.

\(4(6x-1)-(-8)\)

Solution

24x + 4

Try it.

\(14(c-1)-8(c-6)\)

Try it.

\(11(n-7)-5(n-1)\)

Solution

6n − 72

Try it.

\(6(7y+8)-(30y-15)\)

Try it.

\(7(3n+9)-(4n-13)\)

Solution

17n + 76

Evaluate Expressions Using the Distributive Property

In the following exercises, evaluate both expressions for the given value.

Try it.

If \(v=-2,\) evaluate

  1. ⓐ \(\ 6(4v+7)\)
  2. ⓑ \(\ 6\cdot 4v+6\cdot 7\)

Try it.

If \(u=-1,\) evaluate

  1. ⓐ \(\ 8(5u+12)\)
  2. ⓑ \(\ 8\cdot 5u+8\cdot 12\)

Solution

  1. ⓐ 56
  2. ⓑ 56

Try it.

If \(n=\frac{2}{3},\) evaluate

  1. ⓐ \(\ 3(n+\frac{5}{6})\)
  2. ⓑ \(\ 3\cdot n+3\cdot \frac{5}{6}\)

Try it.

If \(y=\frac{3}{4},\) evaluate

  1. ⓐ \(\ 4(y+\frac{3}{8})\)
  2. ⓑ \(\ 4\cdot y+4\cdot \frac{3}{8}\)

Solution

  1. ⓐ \(\ \frac{9}{2}\)
  2. ⓑ \(\ \frac{9}{2}\)

Try it.

If \(y=\frac{7}{12},\) evaluate

  1. ⓐ \(\ -3(4y+15)\)
  2. ⓑ \(\ -3\cdot 4y+(-3)\cdot 15\)

Try it.

If \(p=\frac{23}{30},\) evaluate

  1. ⓐ \(\ -6(5p+11)\)
  2. ⓑ \(\ -6\cdot 5p+(-6)\cdot 11\)

Solution

  1. ⓐ −89
  2. ⓑ −89

Try it.

If \(m=0.4,\) evaluate

  1. ⓐ \(\ -10(3m-0.9)\)
  2. ⓑ \(\ -10\cdot 3m-(-10)(0.9)\)

Try it.

If \(n=0.75,\) evaluate

  1. ⓐ \(\ -100(5n+1.5)\)
  2. ⓑ \(\ -100\cdot 5n+(-100)(1.5)\)

Solution

  1. ⓐ −525
  2. ⓑ −525

Try it.

If \(y=-25,\) evaluate

  1. ⓐ \(\ -(y-25)\)
  2. ⓑ \(\ -y+25\)

Try it.

If \(w=-80,\) evaluate

  1. ⓐ \(\ -(w-80)\)
  2. ⓑ \(\ -w+80\)

Solution

  1. ⓐ 160
  2. ⓑ 160

Try it.

If \(p=0.19,\) evaluate

  1. ⓐ \(\ -(p+0.72)\)
  2. ⓑ \(\ -p-0.72\)

Try it.

If \(q=0.55,\) evaluate

  1. ⓐ \(\ -(q+0.48)\)
  2. ⓑ \(\ -q-0.48\)

Solution

  1. ⓐ −1.03
  2. ⓑ −1.03

Try it.

Simplify \(8(x-\frac{1}{4})\) using the distributive property and explain each step.

Try it.

Explain how you can multiply \(4(\text{\$5.97})\) without paper or a calculator by thinking of \(\text{\$5.97}\) as \(6-0.03\) and then using the distributive property.

Solution

Answers will vary.

ⓐ After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

ⓑ What does this checklist tell you about your mastery of this section? What steps will you take to improve?

Condensed: the full section is in OpenStax Prealgebra 2e.

Nu jij. Geen rekenmachine regelt deze, maar de stukken ervan zijn berekenbaar. Probeer er een hieronder, of typ je eigen.

Praktijk (40)

Probeer ze eerst op papier. Onthul het antwoord om te controleren; geverifieerde kunnen worden geopend in de oplossing voor elke stap.

  1. Multiply: \(3(0.25).\)

    Onthul het antwoord

    \(0.75\)

  2. Simplify: \(10-(-2)(3).\)

    Onthul het antwoord

    \(16\)

  3. Combine like terms: \(9y+17+3y-2.\)

    Onthul het antwoord

    \(12y+15\)

  4. Simplify: \(3(x+4).\)

    Onthul het antwoord
    \(3(x+4)\)
    Distribute.\(3\cdot x+3\cdot 4\)
    Multiply.\(3x+12\)

  5. Simplify: \(4(x+2).\)

    Onthul het antwoord

    4x + 8

  6. Simplify: \(6(x+7).\)

    Onthul het antwoord

    6x + 42

  7. Simplify: \(6(5y+1).\)

    Onthul het antwoord
    Distribute.
    Multiply.

  8. Simplify: \(9(3y+8).\)

    Onthul het antwoord

    27y + 72

  9. Simplify: \(5(5w+9).\)

    Onthul het antwoord

    25w + 45

  10. Simplify: \(2(x-3).\)

    Onthul het antwoord
    Distribute.
    Multiply.

  11. Simplify: \(7(x-6).\)

    Onthul het antwoord

    7x − 42

  12. Simplify: \(8(x-5).\)

    Onthul het antwoord

    8x − 40

  13. Simplify: \(\frac{3}{4}(n+12).\)

    Onthul het antwoord
    Distribute.
    Simplify.

  14. Simplify: \(\frac{2}{5}(p+10).\)

    Onthul het antwoord

    \(\frac{2}{5}p+4\)

  15. Simplify: \(\frac{3}{7}(u+21).\)

    Onthul het antwoord

    \(\frac{3}{7}u+9\)

  16. Simplify: \(8(\frac{3}{8}x+\frac{1}{4}).\)

    Onthul het antwoord
    Distribute.
    Multiply.

  17. Simplify: \(6(\frac{5}{6}y+\frac{1}{2}).\)

    Onthul het antwoord

    5y + 3

  18. Simplify: \(12(\frac{1}{3}n+\frac{3}{4}).\)

    Onthul het antwoord

    4n + 9

  19. Simplify: \(100(0.3+0.25q).\)

    Onthul het antwoord
    Distribute.
    Multiply.

  20. Simplify: \(100(0.7+0.15p).\)

    Onthul het antwoord

    70 + 15p

  21. Simplify: \(100(0.04+0.35d).\)

    Onthul het antwoord

    4 + 35d

  22. Simplify: \(m(n-4).\)

    Onthul het antwoord
    Distribute.
    Multiply.

    Notice that we wrote \(m\cdot 4\ \text{as}\ 4m.\) We can do this because of the Commutative Property of Multiplication. When a term is the product of a number and a variable, we write the number first.

  23. Simplify: \(r(s-2).\)

    Onthul het antwoord

    rs − 2r

  24. Simplify: \(y(z-8).\)

    Onthul het antwoord

    yz − 8y

  25. Simplify: \((x+8)p.\)

    Onthul het antwoord
    Distribute.

  26. Simplify: \((x+2)p.\)

    Onthul het antwoord

    xp + 2p

  27. Simplify: \((y+4)q.\)

    Onthul het antwoord

    yq + 4q

  28. Simplify: \(-2(4y+1).\)

    Onthul het antwoord
    Distribute.
    Simplify.

  29. Simplify: \(-3(6m+5).\)

    Onthul het antwoord

    −18m − 15

  30. Simplify: \(-6(8n+11).\)

    Onthul het antwoord

    −48n − 66

  31. Simplify: \(-11(4-3a).\)

    Onthul het antwoord
    Distribute.
    Multiply.
    Simplify.

    You could also write the result as \(33a-44.\) Do you know why?

  32. Simplify: \(-5(2-3a).\)

    Onthul het antwoord

    −10 + 15a

  33. Simplify: \(-7(8-15y).\)

    Onthul het antwoord

    −56 + 105y

  34. Simplify: \(-(y+5).\)

    Onthul het antwoord
    Multiplying by −1 results in the opposite.
    Distribute.
    Simplify.
    Simplify.

  35. Simplify: \(-(z-11).\)

    Onthul het antwoord

    −z + 11

  36. Simplify: \(-(x-4).\)

    Onthul het antwoord

    −x + 4

  37. Simplify: \(8-2(x+3).\)

    Onthul het antwoord
    Distribute.
    Multiply.
    Combine like terms.

  38. Simplify: \(9-3(x+2).\)

    Onthul het antwoord

    −3x + 3

  39. Simplify: \(7x-5(x+4).\)

    Onthul het antwoord

    2x − 20

  40. Simplify: \(4(x-8)-(x+3).\)

    Onthul het antwoord
    Distribute.
    Combine like terms.
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Hoe: Distributive Property

  1. Simplify expressions using the distributive property
  2. Evaluate expressions using the distributive property
  3. If

Vragen die mensen stellen

Why does the order of operations matter?

Because 2 + 3 × 4 would otherwise be two different numbers. The convention (brackets, exponents, multiplication and division, addition and subtraction) exists so every reader gets the same value from the same expression.

How do I check an arithmetic answer?

Estimate first (round every number and compute roughly), then compare. If the estimate and the exact answer disagree by more than a little, one of them is wrong. The solver shows every operation, so you can find which line went astray.

Why are fractions harder than decimals?

They are not harder, they are more exact: 1/3 is a precise number, 0.333 is an approximation. Fractions need a common denominator to add, which is the one extra step people trip on.

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