x^2-25x-100=100

Solution for x^2-25x-100=100 equation:

x^2-25x-100=100

We move all terms to the left:

x^2-25x-100-(100)=0

We add all the numbers together, and all the variables

x^2-25x-200=0

a = 1; b = -25; c = -200;
Δ = b2-4ac
Δ = -252-4·1·(-200)
Δ = 1425
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:

$\sqrt{\Delta}=\sqrt{1425}=\sqrt{25*57}=\sqrt{25}*\sqrt{57}=5\sqrt{57}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-25)-5\sqrt{57}}{2*1}=\frac{25-5\sqrt{57}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-25)+5\sqrt{57}}{2*1}=\frac{25+5\sqrt{57}}{2}
$