V=h*h+8*h-2

Solution for V=h*h+8*h-2 equation:

=V*V+8V-2

We move all terms to the left:

-(V*V+8V-2)=0

We add all the numbers together, and all the variables

-(8V+V*V-2)=0

We get rid of parentheses

-8V-V*V+2=0

Wy multiply elements

-1V^2-8V+2=0

a = -1; b = -8; c = +2;
Δ = b2-4ac
Δ = -82-4·(-1)·2
Δ = 72
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$V_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$V_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{72}=\sqrt{36*2}=\sqrt{36}*\sqrt{2}=6\sqrt{2}$
$V_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-8)-6\sqrt{2}}{2*-1}=\frac{8-6\sqrt{2}}{-2}
$
$V_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-8)+6\sqrt{2}}{2*-1}=\frac{8+6\sqrt{2}}{-2}
$