Question

Factorise: 3m-n)^2 -m(-2n)^2
Step by step explanation.
Please answer my question as fast as possible.​

Answer 1

Answer:

$9 {m}^{2} + {n}^{2} - 6mn \: - 4m {n}^{2}$

Step-by-step explanation:

Expand using

${(a - b)}^{2} = {a}^{2} + {b}^{2} - 2ab$