x(x+65)+25=90

Solution for x(x+65)+25=90 equation:

x(x+65)+25=90

We move all terms to the left:

x(x+65)+25-(90)=0

We add all the numbers together, and all the variables

x(x+65)-65=0

We multiply parentheses

x^2+65x-65=0

a = 1; b = 65; c = -65;
Δ = b2-4ac
Δ = 652-4·1·(-65)
Δ = 4485
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(65)-\sqrt{4485}}{2*1}=\frac{-65-\sqrt{4485}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(65)+\sqrt{4485}}{2*1}=\frac{-65+\sqrt{4485}}{2}
$