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

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

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

We add all the numbers together, and all the variables

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

We multiply parentheses ..

(-4y^2+8y-9y+18)=0

We get rid of parentheses

-4y^2+8y-9y+18=0

We add all the numbers together, and all the variables

-4y^2-1y+18=0

a = -4; b = -1; c = +18;
Δ = b2-4ac
Δ = -12-4·(-4)·18
Δ = 289
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{289}=17$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-1)-17}{2*-4}=\frac{-16}{-8}
=+2
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-1)+17}{2*-4}=\frac{18}{-8}
=-2+1/4
$