3(r)=3.14r^2

Solution for 3(r)=3.14r^2 equation:

3(r)=3.14r^2

We move all terms to the left:

3(r)-(3.14r^2)=0

We get rid of parentheses

-3.14r^2+3r=0

a = -3.14; b = 3; c = 0;
Δ = b2-4ac
Δ = 32-4·(-3.14)·0
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(3)-3}{2*-3.14}=\frac{-6}{-6.28}
=1/1.0466666666667
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(3)+3}{2*-3.14}=\frac{0}{-6.28}
=0
$