5y+2y(3-y)=15

Solution for 5y+2y(3-y)=15 equation:

5y+2y(3-y)=15

We move all terms to the left:

5y+2y(3-y)-(15)=0

We add all the numbers together, and all the variables

5y+2y(-1y+3)-15=0

We multiply parentheses

-2y^2+5y+6y-15=0

We add all the numbers together, and all the variables

-2y^2+11y-15=0

a = -2; b = 11; c = -15;
Δ = b2-4ac
Δ = 112-4·(-2)·(-15)
Δ = 1
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1}=1$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(11)-1}{2*-2}=\frac{-12}{-4}
=+3
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(11)+1}{2*-2}=\frac{-10}{-4}
=2+1/2
$