141.3=r^2*5

Solution for 141.3=r^2*5 equation:

141.3=r^2*5

We move all terms to the left:

141.3-(r^2*5)=0

We get rid of parentheses

-r^2*5+141.3=0

Wy multiply elements

-5r^2+141.3=0

a = -5; b = 0; c = +141.3;
Δ = b2-4ac
Δ = 02-4·(-5)·141.3
Δ = 2826
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{2826}=\sqrt{9*314}=\sqrt{9}*\sqrt{314}=3\sqrt{314}$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-3\sqrt{314}}{2*-5}=\frac{0-3\sqrt{314}}{-10}
=-\frac{3\sqrt{314}}{-10}
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+3\sqrt{314}}{2*-5}=\frac{0+3\sqrt{314}}{-10}
=\frac{3\sqrt{314}}{-10}
$