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

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

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

We add all the numbers together, and all the variables

(x+4)(-3x+16)=0

We multiply parentheses ..

(-3x^2+16x-12x+64)=0

We get rid of parentheses

-3x^2+16x-12x+64=0

We add all the numbers together, and all the variables

-3x^2+4x+64=0

a = -3; b = 4; c = +64;
Δ = b2-4ac
Δ = 42-4·(-3)·64
Δ = 784
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{784}=28$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(4)-28}{2*-3}=\frac{-32}{-6}
=5+1/3
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(4)+28}{2*-3}=\frac{24}{-6}
=-4
$