(x+5)(x)=28

Solution for (x+5)(x)=28 equation:

(x+5)(x)=28

We move all terms to the left:

(x+5)(x)-(28)=0

We multiply parentheses

x^2+5x-28=0

a = 1; b = 5; c = -28;
Δ = b2-4ac
Δ = 52-4·1·(-28)
Δ = 137
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-\sqrt{137}}{2*1}=\frac{-5-\sqrt{137}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+\sqrt{137}}{2*1}=\frac{-5+\sqrt{137}}{2}
$