7y^2-6y-20=0

Solution for 7y^2-6y-20=0 equation:

7y^2-6y-20=0

a = 7; b = -6; c = -20;
Δ = b2-4ac
Δ = -62-4·7·(-20)
Δ = 596
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{596}=\sqrt{4*149}=\sqrt{4}*\sqrt{149}=2\sqrt{149}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-6)-2\sqrt{149}}{2*7}=\frac{6-2\sqrt{149}}{14}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-6)+2\sqrt{149}}{2*7}=\frac{6+2\sqrt{149}}{14}
$