(3-y)(2y-9)=0

Solution for (3-y)(2y-9)=0 equation:

(3-y)(2y-9)=0

We add all the numbers together, and all the variables

(-1y+3)(2y-9)=0

We multiply parentheses ..

(-2y^2+9y+6y-27)=0

We get rid of parentheses

-2y^2+9y+6y-27=0

We add all the numbers together, and all the variables

-2y^2+15y-27=0

a = -2; b = 15; c = -27;
Δ = b2-4ac
Δ = 152-4·(-2)·(-27)
Δ = 9
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{9}=3$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(15)-3}{2*-2}=\frac{-18}{-4}
=4+1/2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(15)+3}{2*-2}=\frac{-12}{-4}
=+3
$