(4-7y)(7+4y)=0

Solution for (4-7y)(7+4y)=0 equation:

(4-7y)(7+4y)=0

We add all the numbers together, and all the variables

(-7y+4)(4y+7)=0

We multiply parentheses ..

(-28y^2-49y+16y+28)=0

We get rid of parentheses

-28y^2-49y+16y+28=0

We add all the numbers together, and all the variables

-28y^2-33y+28=0

a = -28; b = -33; c = +28;
Δ = b2-4ac
Δ = -332-4·(-28)·28
Δ = 4225
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{4225}=65$
$y_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-33)-65}{2*-28}=\frac{-32}{-56}
=4/7
$
$y_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-33)+65}{2*-28}=\frac{98}{-56}
=-1+3/4
$