X2+15x-1620=0

Solution for X2+15x-1620=0 equation:

X2+15X-1620=0

We add all the numbers together, and all the variables

X^2+15X-1620=0

a = 1; b = 15; c = -1620;
Δ = b2-4ac
Δ = 152-4·1·(-1620)
Δ = 6705
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:

$\sqrt{\Delta}=\sqrt{6705}=\sqrt{9*745}=\sqrt{9}*\sqrt{745}=3\sqrt{745}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-3\sqrt{745}}{2*1}=\frac{-15-3\sqrt{745}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+3\sqrt{745}}{2*1}=\frac{-15+3\sqrt{745}}{2}
$