Question

Select the sequence which is not an arithmetic sequence.

• A. $2,4,6,8,...$
• B. $1,2,4,7,11,16,...$
• C. $3,6,9,12,...$

Answer 1

The correct option is B $1,2,4,7,11,16,...$

$\underset{–}{ConceptInvolved:}$

When the successive term in a numerical pattern is formed by adding a fixed constant value to the previous term, the sequence obtained is an arithmetic sequence.

$\underset{–}{Method:}$

$3,6,9,12,..$
In this sequence, successive terms are obtained by adding 3(a fixed constant value) to the previous term. So, this is an arithmetic sequence.

$2,4,6,8,...$
In this sequence, successive terms are obtained by adding $2$ (a fixed constant value) to the previous term. So, this is an arithmetic sequence.

$1,2,4,7,11,16,...$
In this sequence, successive terms are not obtained by adding a fixed constant value to the previous term. Like for instance,

$2=1+1$
$4=2+2$
$7=4+3$ and so on.

Here a fixed constant value is not added to the previous term to obtain the successive term. So, this sequence is not an arithmetic sequence.