25x=5x2-15

Solution for 25x=5x2-15 equation:

25x=5x^2-15

We move all terms to the left:

25x-(5x^2-15)=0

We get rid of parentheses

-5x^2+25x+15=0

a = -5; b = 25; c = +15;
Δ = b2-4ac
Δ = 252-4·(-5)·15
Δ = 925
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:

$\sqrt{\Delta}=\sqrt{925}=\sqrt{25*37}=\sqrt{25}*\sqrt{37}=5\sqrt{37}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(25)-5\sqrt{37}}{2*-5}=\frac{-25-5\sqrt{37}}{-10}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(25)+5\sqrt{37}}{2*-5}=\frac{-25+5\sqrt{37}}{-10}
$