Solve any maths problem
Equations, derivatives, integrals, matrices, triangles, primes, statistics, or a word problem the tutor breaks into parts.
Step by step
- \pi r^{2} = 50
Start from the equation as given.
- \pi r^{2} - 50 = 0
Bring everything to one side and collect like terms so the right-hand side is 0.
- a = \pi,\quad b = 0,\quad c = -50
Read off the coefficients of the standard form ax² + bx + c = 0.
- \Delta = b^2 - 4ac = (0)^2 - 4(\pi)(-50) = 200 \pi
It does not factor nicely, so use the discriminant Δ = b² − 4ac.
- r = \frac{-b \pm \sqrt{\Delta}}{2a} = \frac{0 \pm \sqrt{200 \pi}}{2 \pi}
Δ > 0, so there are two distinct real roots. Substitute into the quadratic formula.
- r = \frac{5 \sqrt{2}}{\sqrt{\pi}} \approx 3.9894 \quad\text{or}\quad r = - \frac{5 \sqrt{2}}{\sqrt{\pi}} \approx -3.9894
Simplify each root.
Reveal the answer
r = \frac{5 \sqrt{2}}{\sqrt{\pi}} \quad\text{or}\quad r = - \frac{5 \sqrt{2}}{\sqrt{\pi}}