a^2-11a-180=0

Solution for a^2-11a-180=0 equation:

a^2-11a-180=0

a = 1; b = -11; c = -180;
Δ = b2-4ac
Δ = -112-4·1·(-180)
Δ = 841
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{841}=29$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-11)-29}{2*1}=\frac{-18}{2}
=-9
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-11)+29}{2*1}=\frac{40}{2}
=20
$