Question

find (p+q)^3 - (p-q)^3 - 6q(p^2-q^2)​

Answer 1

Step-by-step explanation:

->p3+q3+3p2q+3pq2-{p3+q3-3p2q+3q2p}-6 p2q(p2-q2)

->p3+q3+3p2q+3q2p-p3-q3+3p2q-3q2p-6qp2+6q3p2

->6p2q-6qp2+6q3p2

->6p2q(1-1+q2)

->6p2q(q2)

actually some variables in 2nd stage gets eliminated...and hence u receive the remaining variable in the 3rd stage.