V=(30-2x)(25-2)(x)

Solution for V=(30-2x)(25-2)(x) equation:

=(30-2V)(25-2)(V)

We move all terms to the left:

-((30-2V)(25-2)(V))=0

We add all the numbers together, and all the variables

-((-2V+30)23V)=0


We calculate terms in parentheses: -((-2V+30)23V), so:

(-2V+30)23V

We multiply parentheses

-46V^2+690V

Back to the equation:

-(-46V^2+690V)


We get rid of parentheses

46V^2-690V=0

a = 46; b = -690; c = 0;
Δ = b2-4ac
Δ = -6902-4·46·0
Δ = 476100
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$V_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$V_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{476100}=690$
$V_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-690)-690}{2*46}=\frac{0}{92}
=0
$
$V_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-690)+690}{2*46}=\frac{1380}{92}
=15
$