(7x-14)(x+9)=0

Solution for (7x-14)(x+9)=0 equation:

(7x-14)(x+9)=0

We multiply parentheses ..

(+7x^2+63x-14x-126)=0

We get rid of parentheses

7x^2+63x-14x-126=0

We add all the numbers together, and all the variables

7x^2+49x-126=0

a = 7; b = 49; c = -126;
Δ = b2-4ac
Δ = 492-4·7·(-126)
Δ = 5929
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5929}=77$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(49)-77}{2*7}=\frac{-126}{14}
=-9
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(49)+77}{2*7}=\frac{28}{14}
=2
$