(7x-7)(2x+8)=0

Solution for (7x-7)(2x+8)=0 equation:

(7x-7)(2x+8)=0

We multiply parentheses ..

(+14x^2+56x-14x-56)=0

We get rid of parentheses

14x^2+56x-14x-56=0

We add all the numbers together, and all the variables

14x^2+42x-56=0

a = 14; b = 42; c = -56;
Δ = b2-4ac
Δ = 422-4·14·(-56)
Δ = 4900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4900}=70$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(42)-70}{2*14}=\frac{-112}{28}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(42)+70}{2*14}=\frac{28}{28}
=1
$