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

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

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

We multiply parentheses ..

7(+m^2-2m-4m+8)=0

We multiply parentheses

7m^2-14m-28m+56=0

We add all the numbers together, and all the variables

7m^2-42m+56=0

a = 7; b = -42; c = +56;
Δ = b2-4ac
Δ = -422-4·7·56
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{-(-42)-14}{2*7}=\frac{28}{14}
=2
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(-42)+14}{2*7}=\frac{56}{14}
=4
$