8x(7-5x)=0

Solution for 8x(7-5x)=0 equation:

8x(7-5x)=0

We add all the numbers together, and all the variables

8x(-5x+7)=0

We multiply parentheses

-40x^2+56x=0

a = -40; b = 56; c = 0;
Δ = b2-4ac
Δ = 562-4·(-40)·0
Δ = 3136
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{3136}=56$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(56)-56}{2*-40}=\frac{-112}{-80}
=1+2/5
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(56)+56}{2*-40}=\frac{0}{-80}
=0
$