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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(+2x^2-9x+16x-72)=0

We get rid of parentheses

2x^2-9x+16x-72=0

We add all the numbers together, and all the variables

2x^2+7x-72=0

a = 2; b = 7; c = -72;
Δ = b2-4ac
Δ = 72-4·2·(-72)
Δ = 625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{625}=25$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-25}{2*2}=\frac{-32}{4}
=-8
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+25}{2*2}=\frac{18}{4}
=4+1/2
$