(X+5)(x+4)=112

Solution for (X+5)(x+4)=112 equation:

(X+5)(X+4)=112

We move all terms to the left:

(X+5)(X+4)-(112)=0

We multiply parentheses ..

(+X^2+4X+5X+20)-112=0

We get rid of parentheses

X^2+4X+5X+20-112=0

We add all the numbers together, and all the variables

X^2+9X-92=0

a = 1; b = 9; c = -92;
Δ = b2-4ac
Δ = 92-4·1·(-92)
Δ = 449
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{-(9)-\sqrt{449}}{2*1}=\frac{-9-\sqrt{449}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(9)+\sqrt{449}}{2*1}=\frac{-9+\sqrt{449}}{2}
$