a^2+18a-73=0

Solution for a^2+18a-73=0 equation:

a^2+18a-73=0

a = 1; b = 18; c = -73;
Δ = b2-4ac
Δ = 182-4·1·(-73)
Δ = 616
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{616}=\sqrt{4*154}=\sqrt{4}*\sqrt{154}=2\sqrt{154}$
$a_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(18)-2\sqrt{154}}{2*1}=\frac{-18-2\sqrt{154}}{2}
$
$a_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(18)+2\sqrt{154}}{2*1}=\frac{-18+2\sqrt{154}}{2}
$