(h-8)(h-9)=12

Solution for (h-8)(h-9)=12 equation:

(h-8)(h-9)=12

We move all terms to the left:

(h-8)(h-9)-(12)=0

We multiply parentheses ..

(+h^2-9h-8h+72)-12=0

We get rid of parentheses

h^2-9h-8h+72-12=0

We add all the numbers together, and all the variables

h^2-17h+60=0

a = 1; b = -17; c = +60;
Δ = b2-4ac
Δ = -172-4·1·60
Δ = 49
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$h_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$h_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{49}=7$
$h_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-17)-7}{2*1}=\frac{10}{2}
=5
$
$h_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-17)+7}{2*1}=\frac{24}{2}
=12
$