Question

Express $49$ as the sum of $7$ odd numbers.
Express $121$ as the sum of $11$ odd numbers.

• A. $1+3+5+7+9+11$
  $1+3+5+7+9+11+13+15+19$
• B. $1+3+5+7+9+11+13$
  $1+3+5+7+9+11+13+15+19+21$
• C. $1+3+5+7+9+11$
  $1+3+5+7+9+11+13+15+19+21$
• D. $1+3+5+7+9+11+13$
  $1+3+5+7+9+11+13+15+19$

Answer 1

The correct option is B $1+3+5+7+9+11+13$

$1+3+5+7+9+11+13+15+19+21$
$49=7^2=$ sum of first $7$ odd numbers.
So, $49=1+3+5+7+9+11+13$.
Similarly, $121={11}^2=$ sum of first $11$ odd numbers.
So, $121=1+3+5+7+9+11+13+15+19+21$