Q16 of 84 Page 5

Find whether -150 is a term of the A.P. 17, 12, 12, 7, 2, ….? (CBSE 2011)

We know,

a_n = a + ( n – 1) d

So,

d = 12 – 17

= - 5

-150 = 17 + ( n – 1) (-5)

- 150 = 17 – 5n + 5

- 150 = 22 – 5n

- 150 – 22 = -5n

- 172 = -5n

n = 34.4

Which is not possible.

Hence – 150 cannot be term of the given A.P.

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