Question

find the sum of the first ten terms of an arithmetic series if the first term is 3 and the last term is 39a. 190b.210c.230d.275

Answer 1

Given the first term is 3 and the last term is 39.

Recall that the sum is given as:

`S_n=(n)/(2)(a_1+a_n)`

Substituting in the above equation gives:

`\begin{gathered} S_n=(10)/(2)(3+39) \\ S_n=5(42) \\ S_n=210 \end{gathered}`

Therefore, option (a) is correct.