(X+9)(c+7)=0

Solution for (X+9)(c+7)=0 equation:

(X+9)(X+7)=0

We multiply parentheses ..

(+X^2+7X+9X+63)=0

We get rid of parentheses

X^2+7X+9X+63=0

We add all the numbers together, and all the variables

X^2+16X+63=0

a = 1; b = 16; c = +63;
Δ = b2-4ac
Δ = 162-4·1·63
Δ = 4
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4}=2$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-2}{2*1}=\frac{-18}{2}
=-9
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+2}{2*1}=\frac{-14}{2}
=-7
$