(7x-56)(4x+16)=0

Solution for (7x-56)(4x+16)=0 equation:

(7x-56)(4x+16)=0

We multiply parentheses ..

(+28x^2+112x-224x-896)=0

We get rid of parentheses

28x^2+112x-224x-896=0

We add all the numbers together, and all the variables

28x^2-112x-896=0

a = 28; b = -112; c = -896;
Δ = b2-4ac
Δ = -1122-4·28·(-896)
Δ = 112896
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{112896}=336$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-112)-336}{2*28}=\frac{-224}{56}
=-4
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-112)+336}{2*28}=\frac{448}{56}
=8
$