196=-x^2+100x

Solution for 196=-x^2+100x equation:

196=-x^2+100x

We move all terms to the left:

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

We get rid of parentheses

x^2-100x+196=0

a = 1; b = -100; c = +196;
Δ = b2-4ac
Δ = -1002-4·1·196
Δ = 9216
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9216}=96$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-100)-96}{2*1}=\frac{4}{2}
=2
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-100)+96}{2*1}=\frac{196}{2}
=98
$