4y-3y(y-5)=15

Solution for 4y-3y(y-5)=15 equation:

4y-3y(y-5)=15

We move all terms to the left:

4y-3y(y-5)-(15)=0

We multiply parentheses

-3y^2+4y+15y-15=0

We add all the numbers together, and all the variables

-3y^2+19y-15=0

a = -3; b = 19; c = -15;
Δ = b2-4ac
Δ = 192-4·(-3)·(-15)
Δ = 181
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(19)-\sqrt{181}}{2*-3}=\frac{-19-\sqrt{181}}{-6}
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(19)+\sqrt{181}}{2*-3}=\frac{-19+\sqrt{181}}{-6}
$