X2-13x-140=0

Solution for X2-13x-140=0 equation:

X2-13X-140=0

We add all the numbers together, and all the variables

X^2-13X-140=0

a = 1; b = -13; c = -140;
Δ = b2-4ac
Δ = -132-4·1·(-140)
Δ = 729
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{729}=27$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-13)-27}{2*1}=\frac{-14}{2}
=-7
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-13)+27}{2*1}=\frac{40}{2}
=20
$