(88-2x)(90+5x)=0

Solution for (88-2x)(90+5x)=0 equation:

(88-2x)(90+5x)=0

We add all the numbers together, and all the variables

(-2x+88)(5x+90)=0

We multiply parentheses ..

(-10x^2-180x+440x+7920)=0

We get rid of parentheses

-10x^2-180x+440x+7920=0

We add all the numbers together, and all the variables

-10x^2+260x+7920=0

a = -10; b = 260; c = +7920;
Δ = b2-4ac
Δ = 2602-4·(-10)·7920
Δ = 384400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{384400}=620$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(260)-620}{2*-10}=\frac{-880}{-20}
=+44
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(260)+620}{2*-10}=\frac{360}{-20}
=-18
$