7x^2-56x-115=0

Solution for 7x^2-56x-115=0 equation:

7x^2-56x-115=0

a = 7; b = -56; c = -115;
Δ = b2-4ac
Δ = -562-4·7·(-115)
Δ = 6356
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:

$\sqrt{\Delta}=\sqrt{6356}=\sqrt{4*1589}=\sqrt{4}*\sqrt{1589}=2\sqrt{1589}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-56)-2\sqrt{1589}}{2*7}=\frac{56-2\sqrt{1589}}{14}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-56)+2\sqrt{1589}}{2*7}=\frac{56+2\sqrt{1589}}{14}
$