x^2-9x=1620

Solution for x^2-9x=1620 equation:

x^2-9x=1620

We move all terms to the left:

x^2-9x-(1620)=0

a = 1; b = -9; c = -1620;
Δ = b2-4ac
Δ = -92-4·1·(-1620)
Δ = 6561
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{6561}=81$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-9)-81}{2*1}=\frac{-72}{2}
=-36
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-9)+81}{2*1}=\frac{90}{2}
=45
$