(4w)(10w-7)=0

Solution for (4w)(10w-7)=0 equation:

(4w)(10w-7)=0

We multiply parentheses

40w^2-28w=0

a = 40; b = -28; c = 0;
Δ = b2-4ac
Δ = -282-4·40·0
Δ = 784
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$w_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$w_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{784}=28$
$w_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-28)-28}{2*40}=\frac{0}{80}
=0
$
$w_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-28)+28}{2*40}=\frac{56}{80}
=7/10
$