Question

factorise a²+b²+2ab-81​

Answer 1

Answer:

by rearranging

a^2+2ab+ b^2- 81

( as per comparison between (a+b)^2 identity)

=( a+b) ^2- 81

= ( a+b) ^2 -(9) ^2

=(a+b+9) (a+b-9) ( using a^2-b^2 identity)

hope it will help you