7x^2+13x-8=39x

Solution for 7x^2+13x-8=39x equation:

7x^2+13x-8=39x

We move all terms to the left:

7x^2+13x-8-(39x)=0

We add all the numbers together, and all the variables

7x^2-26x-8=0

a = 7; b = -26; c = -8;
Δ = b2-4ac
Δ = -262-4·7·(-8)
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-26)-30}{2*7}=\frac{-4}{14}
=-2/7
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-26)+30}{2*7}=\frac{56}{14}
=4
$