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Arithmetic Progressions

Question
CBSEENMA10007433

Which of the following are APs ? If they form an AP, find the common difference d and write three more terms.
 –10, –6, –2, 2, ....

Solution

 –10, –6, –2, 2, ....
a2 – a1 = – 6– (–10)
= –6 + 10 = 4
a3 – a2 = –2 – (–6)
= –2 + 6 = 4
a4 – a3 = 2 – (–2)
= 2 + 2 = 4
i.e., ak + 1 – ak is he same every time. So, the given list of numbers forms an A .P. with
the common difference d = 4.
The next three terms are :
2 + 4 = 6, 6 + 4= 10
and 10 + 4 = 14