(x-18)(x+17)=0

Solution for (x-18)(x+17)=0 equation:

(x-18)(x+17)=0

We multiply parentheses ..

(+x^2+17x-18x-306)=0

We get rid of parentheses

x^2+17x-18x-306=0

We add all the numbers together, and all the variables

x^2-1x-306=0

a = 1; b = -1; c = -306;
Δ = b2-4ac
Δ = -12-4·1·(-306)
Δ = 1225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1225}=35$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-35}{2*1}=\frac{-34}{2}
=-17
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+35}{2*1}=\frac{36}{2}
=18
$