Question

The first term of an A.P is $2$and the common difference is $4$ The sum of its $40$ terms will be

• A. $3200$
• B. $1600$
• C. $200$
• D. $2800$

Answer 1

The correct option is A

$3200$

The explanation for the correct answer.

Solve for the sum of $40$terms of the A.P.

The first term of AP,$a=2$

Common difference, $d=4$

Sum of $n$ terms,${\mathit{S}}_{\mathbf{n}}\mathbf{=}\frac{\mathbf{n}}{\mathbf{2}}\left[2a+(n-1)d\right]$

$$\begin{gathered} \Rightarrow S_{40}=20\left[4+39\times 4\right] \\ \Rightarrow S_{40}=3200 \end{gathered}$$

So, the sum of $40$ terms of the A.P. is $3200$

Hence, option(A) is the correct answer.