Question

Find out the following squares by using the identities:
$(10m-9n{)}^2$

Answer 1

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

Here $a=10m,b=9n$

Using this identity, we get

$(10m-9n{)}^2=(10m{)}^2+(9n{)}^2-2\times 10m\times 9n=100m^2+81n^2-180mn$

This is the required answer.