Question

How do you find the fifth term of `(2a+3b)^10`?

Answer 1

`1088640a^6b^4`

Explanation:

In the binomial expansion of `(x+a)^n`, (r+1)th term is written as,

`T_(r+1)= ^nC_r x^(n-r) a^r`. Here n=10, x=2a and b=3b

For 5th term, put r=4 in this formula

`T_5= ^10C_4 (2a)^6 (3b)^4`

= `(10.9.8.7)/(1.2.3.4) (64a^6) (81b^4)`

=`1088640a^6b^4`