x2-90x+1400=0

Solution for x2-90x+1400=0 equation:

x2-90x+1400=0

We add all the numbers together, and all the variables

x^2-90x+1400=0

a = 1; b = -90; c = +1400;
Δ = b2-4ac
Δ = -902-4·1·1400
Δ = 2500
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{2500}=50$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-90)-50}{2*1}=\frac{40}{2}
=20
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-90)+50}{2*1}=\frac{140}{2}
=70
$