(7m)(4m-2)=0

Solution for (7m)(4m-2)=0 equation:

(7m)(4m-2)=0

We multiply parentheses

28m^2-14m=0

a = 28; b = -14; c = 0;
Δ = b2-4ac
Δ = -142-4·28·0
Δ = 196
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

$\sqrt{\Delta}=\sqrt{196}=14$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(-14)-14}{2*28}=\frac{0}{56}
=0
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-14)+14}{2*28}=\frac{28}{56}
=1/2
$