5x(x-5)=15

Solution for 5x(x-5)=15 equation:

5x(x-5)=15

We move all terms to the left:

5x(x-5)-(15)=0

We multiply 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}
$