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Question
Check whether -150 is a term of the A.P. 11, 8, 5, 2, ....
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Solution
For this A.P.,
a = 11
d = a2 − a1
= 8 − 11
= −3
Let −150 be the nth term of this A.P.
We know that,
an = a + (n − 1) d
-150 = 11 + (n - 1)(-3)
-150 = 11 - 3n + 3
-164 = -3n
n = `164/3`
Clearly, n is not an integer.
Therefore, -150 is not a term of this A.P.
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