X=x^2-3x-70

Solution for X=x^2-3x-70 equation:

X=X^2-3X-70

We move all terms to the left:

X-(X^2-3X-70)=0

We get rid of parentheses

-X^2+X+3X+70=0

We add all the numbers together, and all the variables

-1X^2+4X+70=0

a = -1; b = 4; c = +70;
Δ = b2-4ac
Δ = 42-4·(-1)·70
Δ = 296
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:

$\sqrt{\Delta}=\sqrt{296}=\sqrt{4*74}=\sqrt{4}*\sqrt{74}=2\sqrt{74}$
$X_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-2\sqrt{74}}{2*-1}=\frac{-4-2\sqrt{74}}{-2}
$
$X_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+2\sqrt{74}}{2*-1}=\frac{-4+2\sqrt{74}}{-2}
$