x2+20x+100=225

Solution for x2+20x+100=225 equation:

x2+20x+100=225

We move all terms to the left:

x2+20x+100-(225)=0

We add all the numbers together, and all the variables

x^2+20x-125=0

a = 1; b = 20; c = -125;
Δ = b2-4ac
Δ = 202-4·1·(-125)
Δ = 900
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{900}=30$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(20)-30}{2*1}=\frac{-50}{2}
=-25
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(20)+30}{2*1}=\frac{10}{2}
=5
$