X^2+70x-120=0

Solution for X^2+70x-120=0 equation:

X^2+70X-120=0

a = 1; b = 70; c = -120;
Δ = b2-4ac
Δ = 702-4·1·(-120)
Δ = 5380
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:

$\sqrt{\Delta}=\sqrt{5380}=\sqrt{4*1345}=\sqrt{4}*\sqrt{1345}=2\sqrt{1345}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(70)-2\sqrt{1345}}{2*1}=\frac{-70-2\sqrt{1345}}{2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(70)+2\sqrt{1345}}{2*1}=\frac{-70+2\sqrt{1345}}{2}
$