7x(8x-3)=0

Solution for 7x(8x-3)=0 equation:

7x(8x-3)=0

We multiply parentheses

56x^2-21x=0

a = 56; b = -21; c = 0;
Δ = b2-4ac
Δ = -212-4·56·0
Δ = 441
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{441}=21$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-21)-21}{2*56}=\frac{0}{112}
=0
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-21)+21}{2*56}=\frac{42}{112}
=3/8
$