(5+x)x=25

Solution for (5+x)x=25 equation:

(5+x)x=25

We move all terms to the left:

(5+x)x-(25)=0

We add all the numbers together, and all the variables

(x+5)x-25=0

We multiply parentheses

x^2+5x-25=0

a = 1; b = 5; c = -25;
Δ = b2-4ac
Δ = 52-4·1·(-25)
Δ = 125
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:

$\sqrt{\Delta}=\sqrt{125}=\sqrt{25*5}=\sqrt{25}*\sqrt{5}=5\sqrt{5}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(5)-5\sqrt{5}}{2*1}=\frac{-5-5\sqrt{5}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(5)+5\sqrt{5}}{2*1}=\frac{-5+5\sqrt{5}}{2}
$