Question

Find the sum of 10 terms of the sequence 1,3,5,7,…

• A. 98
• B. 100
• C. 102
• D. 104

Answer 1

The correct option is B

100

Every term is of the form 2n + 1, i.e. the sequence is 1,3,5,…

First term, a = 1

Common difference, d = 2

$T_{10}$ = a + (n-1)d=1 + (10 - 1)2 = 19

Sum to n terms =( $\frac{n}{2}$)(a+l) , where l = $T_{10}$

$\Rightarrow$ Sum to 10 terms = ( $\frac{10}{2}$)(1+19)= 100