7x2=-4x+8

Solution for 7x2=-4x+8 equation:

7x^2=-4x+8

We move all terms to the left:

7x^2-(-4x+8)=0

We get rid of parentheses

7x^2+4x-8=0

a = 7; b = 4; c = -8;
Δ = b2-4ac
Δ = 42-4·7·(-8)
Δ = 240
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{240}=\sqrt{16*15}=\sqrt{16}*\sqrt{15}=4\sqrt{15}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-4\sqrt{15}}{2*7}=\frac{-4-4\sqrt{15}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+4\sqrt{15}}{2*7}=\frac{-4+4\sqrt{15}}{14}
$