225=3.14(1)r^2

Solution for 225=3.14(1)r^2 equation:

225=3.14(1)r^2

We move all terms to the left:

225-(3.14(1)r^2)=0

We get rid of parentheses

-3.141r^2+225=0

a = -3.141; b = 0; c = +225;
Δ = b2-4ac
Δ = 02-4·(-3.141)·225
Δ = 2826.9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-\sqrt{2826.9}}{2*-3.141}=\frac{0-\sqrt{2826.9}}{-6.282}
=-\frac{\sqrt{}}{-6.282}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+\sqrt{2826.9}}{2*-3.141}=\frac{0+\sqrt{2826.9}}{-6.282}
=\frac{\sqrt{}}{-6.282}
$