x^2-90x+648=0

Solution for x^2-90x+648=0 equation:

x^2-90x+648=0

a = 1; b = -90; c = +648;
Δ = b2-4ac
Δ = -902-4·1·648
Δ = 5508
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:

$\sqrt{\Delta}=\sqrt{5508}=\sqrt{324*17}=\sqrt{324}*\sqrt{17}=18\sqrt{17}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-90)-18\sqrt{17}}{2*1}=\frac{90-18\sqrt{17}}{2}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-90)+18\sqrt{17}}{2*1}=\frac{90+18\sqrt{17}}{2}
$