(Math Quiz 10 – CT) In the expansion ({left( {2a – 1} right)^6}), the sum of the first three terms is:

• Question:

In the expansion $${\left( {2a – 1} \right)^6}$$, the sum of the first three terms is:

Reference explanation:

$$\begin{array}{l} {\left( {2a – 1} \right)^6}\\ = C_6^0{.2^6}{a^6} – C_6^1{.2^5}{a^5} + C_6^2{.2^4}{a^4} – … \end{array}$$
So the sum of the first 3 terms is $$64{a^6} – 192{a^5} + 240{a^4}$$.