7y(y-4)=35

Solution for 7y(y-4)=35 equation:

7y(y-4)=35

We move all terms to the left:

7y(y-4)-(35)=0

We multiply parentheses

7y^2-28y-35=0

a = 7; b = -28; c = -35;
Δ = b2-4ac
Δ = -282-4·7·(-35)
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{-(-28)-42}{2*7}=\frac{-14}{14}
=-1
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+42}{2*7}=\frac{70}{14}
=5
$