(x+9)(X+7)=126

Solution for (x+9)(X+7)=126 equation:

(x+9)(x+7)=126

We move all terms to the left:

(x+9)(x+7)-(126)=0

We multiply parentheses ..

(+x^2+7x+9x+63)-126=0

We get rid of parentheses

x^2+7x+9x+63-126=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 = 508
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:

$\sqrt{\Delta}=\sqrt{508}=\sqrt{4*127}=\sqrt{4}*\sqrt{127}=2\sqrt{127}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-2\sqrt{127}}{2*1}=\frac{-16-2\sqrt{127}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+2\sqrt{127}}{2*1}=\frac{-16+2\sqrt{127}}{2}
$