(2x-8)(9x+7)=0

Solution for (2x-8)(9x+7)=0 equation:

(2x-8)(9x+7)=0

We multiply parentheses ..

(+18x^2+14x-72x-56)=0

We get rid of parentheses

18x^2+14x-72x-56=0

We add all the numbers together, and all the variables

18x^2-58x-56=0

a = 18; b = -58; c = -56;
Δ = b2-4ac
Δ = -582-4·18·(-56)
Δ = 7396
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{7396}=86$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-58)-86}{2*18}=\frac{-28}{36}
=-7/9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-58)+86}{2*18}=\frac{144}{36}
=4
$