2x2+7x-56=91

Solution for 2x2+7x-56=91 equation:

2x^2+7x-56=91

We move all terms to the left:

2x^2+7x-56-(91)=0

We add all the numbers together, and all the variables

2x^2+7x-147=0

a = 2; b = 7; c = -147;
Δ = b2-4ac
Δ = 72-4·2·(-147)
Δ = 1225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1225}=35$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-35}{2*2}=\frac{-42}{4}
=-10+1/2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+35}{2*2}=\frac{28}{4}
=7
$