9/10/2014
If
the coefficients of the 4th
term of (x + y)11
is 165, find the 5th
term.
Scroll down for the solution.
9/10/2014
Solution.
Since,
in general, the relationship between coefficients of the (k
+
1)st
and kth
term of (x + y)n
is nCk
=
(n
– (k
– 1))Ck·nC(k
– 1),
we can find the 5th
term coefficient as: 11
– (4 – 1)C4·165
= 330 so that the 5th
term is: 330x7y4.