How do you find the 5th term in the expansion of the binomial $(5a+6b)^5$ ?

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Answer 1 · 2017-10-14T11:09:25

$32400ab^4$

The fifth term descending a:

$5^1(5C4)a^1 6^4b^4= 5*5*1296a^1b^5=32400ab^4$

Answer 2 · 2017-10-18T00:10:31

$32400ab^4$

The expansion will have six terms starting with $a^5$ and ending with $b^5$
Fifth term will be $5C(5-1)*a^(5-4)*b^4$

Given a as (5a) & b as (6b)

We also know $5C4 = 5C1 = 5$ .

Substituting in the 5^th term, we get

$= 5*(5a)*(6b)^4 = 32400*a*b^4$

How do you find the 5th term in the expansion of the binomial (5a+6b)^5(5a+6b)^5?