math
posted by purple1 .
write the first three terms of the expansion of (ab)^10
what are the last three terms of
(ab)^7

Look up "Pascal's Triangle", you will find it very useful for these type of questions.
If not then ....
(ab)^10
= a^10 + 10a^9(b) + 10*9/2!a^8(b)^2 +
= a^10  10a^9b + 45a^8b^2 + ...