1. ## Expansion

Find the specified 5th term in the expansion of :

(5a+6b)^5

2. Originally Posted by thepride
Find the specified 5th term in the expansion of :

(5a+6b)^5
Use the binomial Theorem

$(x+y)^n=\sum_{k=0}^{n}\binom{n}{k}x^{n-k}y^{k}$

Since the binomial theorem starts at k=0 the fifth term will be when k=4

$\binom{5}{4}(5a)^{5-4}(6b)^4=$

Just simplify from here.

3. Originally Posted by TheEmptySet
Use the binomial Theorem

$(x+y)^n=\sum_{k=0}^{n}\binom{n}{k}x^{n-k}y^{k}$

Since the binomial theorem starts at k=0 the fifth term will be when k=4

$\binom{5}{4}(5a)^{5-4}(6b)^4=$

Just simplify from here.
i think the answer is 32400ab^5 thepride

4. how do i simplify that equation...like what do i do with the 5 and 4 that are on top of each other do i divide??? i answer is useless to me if i don't know how your got it. please show me how you got you answer flexus.