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Question
Is -150 a term of the AP 11, 8, 5, 2, ……?
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Solution
The given AP is 11, 8, 5, 2, ……
Here, a= 11and d = 8 - 11 = - 3
Let the nth term of the given AP be - 150. Then,
an = -150
⇒ 11+ (n-1) × (-3) = - 150 [ an = a + (n-1) d]
⇒ -3n +14 = -150
⇒ -3n = -164
⇒ n= `164/3 = 54 2/3`
But, the number of terms cannot be a fraction.
Hence, -150 is not a term of the given AP.
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