3m*7m=42

Solution for 3m*7m=42 equation:

3m*7m=42

We move all terms to the left:

3m*7m-(42)=0

Wy multiply elements

21m^2-42=0

a = 21; b = 0; c = -42;
Δ = b2-4ac
Δ = 02-4·21·(-42)
Δ = 3528
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{3528}=\sqrt{1764*2}=\sqrt{1764}*\sqrt{2}=42\sqrt{2}$
$m_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-42\sqrt{2}}{2*21}=\frac{0-42\sqrt{2}}{42}
=-\frac{42\sqrt{2}}{42}
=-\sqrt{2}
$
$m_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+42\sqrt{2}}{2*21}=\frac{0+42\sqrt{2}}{42}
=\frac{42\sqrt{2}}{42}
=\sqrt{2}
$