0=x^2-100x+900

Solution for 0=x^2-100x+900 equation:

0=x^2-100x+900

We move all terms to the left:

0-(x^2-100x+900)=0

We add all the numbers together, and all the variables

-(x^2-100x+900)=0

We get rid of parentheses

-x^2+100x-900=0

We add all the numbers together, and all the variables

-1x^2+100x-900=0

a = -1; b = 100; c = -900;
Δ = b2-4ac
Δ = 1002-4·(-1)·(-900)
Δ = 6400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6400}=80$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(100)-80}{2*-1}=\frac{-180}{-2}
=+90
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(100)+80}{2*-1}=\frac{-20}{-2}
=+10
$