(X+9)(x+5)=360

Solution for (X+9)(x+5)=360 equation:

(X+9)(X+5)=360

We move all terms to the left:

(X+9)(X+5)-(360)=0

We multiply parentheses ..

(+X^2+5X+9X+45)-360=0

We get rid of parentheses

X^2+5X+9X+45-360=0

We add all the numbers together, and all the variables

X^2+14X-315=0

a = 1; b = 14; c = -315;
Δ = b2-4ac
Δ = 142-4·1·(-315)
Δ = 1456
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{1456}=\sqrt{16*91}=\sqrt{16}*\sqrt{91}=4\sqrt{91}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(14)-4\sqrt{91}}{2*1}=\frac{-14-4\sqrt{91}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(14)+4\sqrt{91}}{2*1}=\frac{-14+4\sqrt{91}}{2}
$