4r^2=18r-20

Solution for 4r^2=18r-20 equation:

4r^2=18r-20

We move all terms to the left:

4r^2-(18r-20)=0

We get rid of parentheses

4r^2-18r+20=0

a = 4; b = -18; c = +20;
Δ = b2-4ac
Δ = -182-4·4·20
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$r_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-18)-2}{2*4}=\frac{16}{8}
=2
$
$r_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-18)+2}{2*4}=\frac{20}{8}
=2+1/2
$