7x^2+7x-7=8-9x

Solution for 7x^2+7x-7=8-9x equation:

7x^2+7x-7=8-9x

We move all terms to the left:

7x^2+7x-7-(8-9x)=0

We add all the numbers together, and all the variables

7x^2+7x-(-9x+8)-7=0

We get rid of parentheses

7x^2+7x+9x-8-7=0

We add all the numbers together, and all the variables

7x^2+16x-15=0

a = 7; b = 16; c = -15;
Δ = b2-4ac
Δ = 162-4·7·(-15)
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(16)-26}{2*7}=\frac{-42}{14}
=-3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(16)+26}{2*7}=\frac{10}{14}
=5/7
$