What is the fourth term in the expansion of (2xy)5?

1 Answer
Feb 13, 2016

You can find this by using the formula tr+1=nCr×anr×br

Explanation:

r can be found by solving the simple equation tr+1=4 We can immediately eliminate the t, and we find that r is 3. n is the exponent, which is 5 in this case. Note the n and the r are in base at the C.

t4=5C3×2x53×y3

t4=10×4x2(y3)

t4=40x2y3

Your fourth term is 40x2y3.

Practice exercises:

  1. Find the 7th term in (2x+3y)12

  2. Find the middle term of (3xy3)8

Good luck!