25=2x^2-4x

Solution for 25=2x^2-4x equation:

25=2x^2-4x

We move all terms to the left:

25-(2x^2-4x)=0

We get rid of parentheses

-2x^2+4x+25=0

a = -2; b = 4; c = +25;
Δ = b2-4ac
Δ = 42-4·(-2)·25
Δ = 216
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:

$\sqrt{\Delta}=\sqrt{216}=\sqrt{36*6}=\sqrt{36}*\sqrt{6}=6\sqrt{6}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-6\sqrt{6}}{2*-2}=\frac{-4-6\sqrt{6}}{-4}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+6\sqrt{6}}{2*-2}=\frac{-4+6\sqrt{6}}{-4}
$