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

Solution for (2y-1)(y+4)=0 equation:

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

We multiply parentheses ..

(+2y^2+8y-1y-4)=0

We get rid of parentheses

2y^2+8y-1y-4=0

We add all the numbers together, and all the variables

2y^2+7y-4=0

a = 2; b = 7; c = -4;
Δ = b2-4ac
Δ = 72-4·2·(-4)
Δ = 81
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{81}=9$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(7)-9}{2*2}=\frac{-16}{4}
=-4
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(7)+9}{2*2}=\frac{2}{4}
=1/2
$