x^2-85x+400=0

Solution for x^2-85x+400=0 equation:

x^2-85x+400=0

a = 1; b = -85; c = +400;
Δ = b2-4ac
Δ = -852-4·1·400
Δ = 5625
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{5625}=75$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-85)-75}{2*1}=\frac{10}{2}
=5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-85)+75}{2*1}=\frac{160}{2}
=80
$