What is the 4th term of (3x+y)7?

1 Answer
Apr 29, 2015

Consider the binomial expansion of (a+b)n. (r+1)th term in this expansion is written as Tr+1=nCranrbr.

Now comparing the given expression, it can be seen that n=7, a= 3x, b= y and r=3(for getting the 4th term)

Accordingly, T4=7C3(3x)4y3=3581x4y3=2835x4y3