Going through past paper for the above question to find the coefficient of the above expansion & have seen a guide to using my Casio to work out the value of coefficient at x^14 but it errors for this calculation.
n should be bigger than r, shouldn't it?
i.e. n=14 & r=16
nCr = n!/(n-r)!r! which is 14! / -2! 16! so no suprise there, perhaps the indeces are wrong?
So, next example seems more likely; for the coefficient of x^18 for expansion of (1/14 x^2 - 7)^16.
so n=18 & r=16
nCr = 18! / -2! 16! = 153
I have a feeling there is something else, but not sure what it is.
Could someone point in the right direction
Thank you, the 3x term is raised to 14 for the coefficient of that term, but I don't understand why the 1/3 term is squared not raised to 14 too.
Can you apply this to the second example, too.