(5y-2)(y)=72

Solution for (5y-2)(y)=72 equation:

(5y-2)(y)=72

We move all terms to the left:

(5y-2)(y)-(72)=0

We multiply parentheses

5y^2-2y-72=0

a = 5; b = -2; c = -72;
Δ = b2-4ac
Δ = -22-4·5·(-72)
Δ = 1444
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1444}=38$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-2)-38}{2*5}=\frac{-36}{10}
=-3+3/5
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-2)+38}{2*5}=\frac{40}{10}
=4
$