(4y-2)(9-y)=0

Solution for (4y-2)(9-y)=0 equation:

(4y-2)(9-y)=0

We add all the numbers together, and all the variables

(4y-2)(-1y+9)=0

We multiply parentheses ..

(-4y^2+36y+2y-18)=0

We get rid of parentheses

-4y^2+36y+2y-18=0

We add all the numbers together, and all the variables

-4y^2+38y-18=0

a = -4; b = 38; c = -18;
Δ = b2-4ac
Δ = 382-4·(-4)·(-18)
Δ = 1156
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{1156}=34$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(38)-34}{2*-4}=\frac{-72}{-8}
=+9
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(38)+34}{2*-4}=\frac{-4}{-8}
=1/2
$