Binomial coefficient in an expansion
I must "use the binomial theorem to determine the coefficient x^14 in the expansion of (3x^2-1/3)^16".
I find that:
a=3x^2 (I believe)
I write that (sorry but the matrix brackets I cannot make):
(16) (3x^2) ^(16-14+1) (-1/3)^13
= (16) (3x^2)^3 (-1/3)^13
= (16!/(16-13)!13!) (1/? x^6)
This part is how I am getting confused.
Can somebody help me please to continue to solving this question? I must "expressing the coefficient as a fraction in lowest terms" but I don't think I have calculated well above to make the fraction to continue. The book is not showing this kind of difficult examples before we must do the assignment!