5x(5x-31)=72

Solution for 5x(5x-31)=72 equation:

5x(5x-31)=72

We move all terms to the left:

5x(5x-31)-(72)=0

We multiply parentheses

25x^2-155x-72=0

a = 25; b = -155; c = -72;
Δ = b2-4ac
Δ = -1552-4·25·(-72)
Δ = 31225
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:

$\sqrt{\Delta}=\sqrt{31225}=\sqrt{25*1249}=\sqrt{25}*\sqrt{1249}=5\sqrt{1249}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-155)-5\sqrt{1249}}{2*25}=\frac{155-5\sqrt{1249}}{50}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-155)+5\sqrt{1249}}{2*25}=\frac{155+5\sqrt{1249}}{50}
$