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Which term of the AP 24, 21, 18, 15,... ...

Which term of the AP 24, 21, 18, 15,... Is the first negative term?

A

`9th`

B

`10th`

C

`8th`

D

`7th`

Text Solution

Verified by Experts

The correct Answer is:
B
Here a = 24 and d = (21-24) =-3.
Let the nth term of the given AP be the first negative term.
Then, `T_(n) lt 0 rArr {a + (n-1)d} lt 0`
`rArr {24 + (n-1) xx (-3)} lt 0`
`rArr (27-3n) lt 0 rArr 27 lt 3n`
`rArr 3n gt 27 rArr n gt 9.`
`therefore n = 10`
Hence, the 10th term is the first negative term of the given AP.
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