Question

Please Help me to solve this question it came in 9th final exams (CBSE) ​

Answer 1

For expansion you will take the first term as a and second as b.So,the formula is
(a^3-b^3)=a^3-b^3-3*a*b(a-b)
So now put 1/x in a’s position and y/3 in b’s position
Hope this helps