Question

What's the expression for the given sequence of numbers if n indicates 'n'th number?
1, 3, 5, 7, 9.........

• A. 2n + 1
• B. 2n
• C. 2n - 1
• D. 2n + 2

Answer 1

The correct option is C 2n - 1

In the given sequence of numbers,

1st number = 1 = $2\times 1$ - 1
2nd number = 3 = $2\times 2$ - 1
3rd number = 5 = $2\times 3$ - 1
4th number = 7 = $2\times 4$ - 1
. .
. .
. .
. .
nth number = $2\times n$ - 1
= 2n - 1

$\therefore$ The expression for given sequence is 2n - 1.