Y=7x^2-14x-56

Solution for Y=7x^2-14x-56 equation:

=7Y^2-14Y-56

We move all terms to the left:

-(7Y^2-14Y-56)=0

We get rid of parentheses

-7Y^2+14Y+56=0

a = -7; b = 14; c = +56;
Δ = b2-4ac
Δ = 142-4·(-7)·56
Δ = 1764
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1764}=42$
$Y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(14)-42}{2*-7}=\frac{-56}{-14}
=+4
$
$Y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(14)+42}{2*-7}=\frac{28}{-14}
=-2
$