(5y+6)(4-y)=0

Solution for (5y+6)(4-y)=0 equation:

(5y+6)(4-y)=0

We add all the numbers together, and all the variables

(5y+6)(-1y+4)=0

We multiply parentheses ..

(-5y^2+20y-6y+24)=0

We get rid of parentheses

-5y^2+20y-6y+24=0

We add all the numbers together, and all the variables

-5y^2+14y+24=0

a = -5; b = 14; c = +24;
Δ = b2-4ac
Δ = 142-4·(-5)·24
Δ = 676
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{676}=26$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(14)-26}{2*-5}=\frac{-40}{-10}
=+4
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(14)+26}{2*-5}=\frac{12}{-10}
=-1+1/5
$