x(7x-128)=0

Solution for x(7x-128)=0 equation:

x(7x-128)=0

We multiply parentheses

7x^2-128x=0

a = 7; b = -128; c = 0;
Δ = b2-4ac
Δ = -1282-4·7·0
Δ = 16384
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{16384}=128$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-128)-128}{2*7}=\frac{0}{14}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-128)+128}{2*7}=\frac{256}{14}
=18+2/7
$