(X-1)(x+2)=180

Solution for (X-1)(x+2)=180 equation:

(X-1)(X+2)=180

We move all terms to the left:

(X-1)(X+2)-(180)=0

We multiply parentheses ..

(+X^2+2X-1X-2)-180=0

We get rid of parentheses

X^2+2X-1X-2-180=0

We add all the numbers together, and all the variables

X^2+X-182=0

a = 1; b = 1; c = -182;
Δ = b2-4ac
Δ = 12-4·1·(-182)
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(1)-27}{2*1}=\frac{-28}{2}
=-14
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(1)+27}{2*1}=\frac{26}{2}
=13
$