-3y(-3y+19)=15

Solution for -3y(-3y+19)=15 equation:

-3y(-3y+19)=15

We move all terms to the left:

-3y(-3y+19)-(15)=0

We multiply parentheses

9y^2-57y-15=0

a = 9; b = -57; c = -15;
Δ = b2-4ac
Δ = -572-4·9·(-15)
Δ = 3789
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:

$\sqrt{\Delta}=\sqrt{3789}=\sqrt{9*421}=\sqrt{9}*\sqrt{421}=3\sqrt{421}$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-57)-3\sqrt{421}}{2*9}=\frac{57-3\sqrt{421}}{18}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-57)+3\sqrt{421}}{2*9}=\frac{57+3\sqrt{421}}{18}
$