## (Math Quiz 10 – CT) In the expansion ({left( {{a^2} + frac{1}{b}} right)^7}), the 5th term is:

• Question:

In the expansion $${\left( {{a^2} + \frac{1}{b}} \right)^7}$$, the 5th term is:

Reference explanation:

The general term in the above expansion is

$${T_{k + 1}} = C_7^k. {a^{14 – 2k}}. {b^{ – k}}$$

So the 5th term is

$${T_5} = C_7^4. {a^6}. {b^{ – 4}} = 35. {a^6}. {b^{ – 4}}$$.

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