(28+y)*y=288

Solution for (28+y)*y=288 equation:

(28+y)*y=288

We move all terms to the left:

(28+y)*y-(288)=0

We add all the numbers together, and all the variables

(y+28)*y-288=0

We multiply parentheses

y^2+28y-288=0

a = 1; b = 28; c = -288;
Δ = b2-4ac
Δ = 282-4·1·(-288)
Δ = 1936
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1936}=44$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(28)-44}{2*1}=\frac{-72}{2}
=-36
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(28)+44}{2*1}=\frac{16}{2}
=8
$