Question

1,4,7.... -5,-2,1,4.... 3,7,12,18... 11,14,17,20... which of the following term is not an ap​

Answer 1

$\color{darkred} \huge{series \: with \: same \: or \: equal \: diff \: called \: ap \: series}$

In

• above series series with equal difference called ap .....
• otherwise, unequal series in not an ap

Lets do.

1,4,7......

Difference between series is same or equal i.e 3

Hence it is ap

-5,-2,1,4

• Difference between series' is
• -2-(-5)
• -2+5
• 3

same

• 1-(-2)
• 1+2
• 3

Hence difference is equal .It is ap series

11,14,17,20

this series also have equal difference i e 3

Hence it is called ap

3,7,12,18

In this, difference is unequal,so hence it is not an ap...

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