(x-4)(x+3)=72

Solution for (x-4)(x+3)=72 equation:

(x-4)(x+3)=72

We move all terms to the left:

(x-4)(x+3)-(72)=0

We multiply parentheses ..

(+x^2+3x-4x-12)-72=0

We get rid of parentheses

x^2+3x-4x-12-72=0

We add all the numbers together, and all the variables

x^2-1x-84=0

a = 1; b = -1; c = -84;
Δ = b2-4ac
Δ = -12-4·1·(-84)
Δ = 337
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-\sqrt{337}}{2*1}=\frac{1-\sqrt{337}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+\sqrt{337}}{2*1}=\frac{1+\sqrt{337}}{2}
$