x^2-10x-70=5

Solution for x^2-10x-70=5 equation:

x^2-10x-70=5

We move all terms to the left:

x^2-10x-70-(5)=0

We add all the numbers together, and all the variables

x^2-10x-75=0

a = 1; b = -10; c = -75;
Δ = b2-4ac
Δ = -102-4·1·(-75)
Δ = 400
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{400}=20$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-10)-20}{2*1}=\frac{-10}{2}
=-5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-10)+20}{2*1}=\frac{30}{2}
=15
$