Question

3. Which term of the AP, 24,21, 18, 15,---- is
the first negative term?​

Answer 1

Answer:

Step-by-step explanation:

Let nth term of the given AP be the first negative term.

AP = 24 , 21 , 18,15....

Here,

First term ( a ) = 24

Common difference ( d ) = 21-24 = -4.

Then , Tn <0

=> { a + ( n - 1 ) × d } <0

=> { 24 + ( n - 1 ) × -3 } <0

=> 27 - 3n <0

=> 27 < 3n

=> 3n > 27

=> n = 9.

n = 10

Hence,The 10th term is the first negative term of the given AP.

Answer 2

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$here \: a = 24 \: and \: d = (21 - 24) = - 3 \\ let \: the \: nth \: term \: of \: the \: given \: ap \: be \: the \: first \: negative \: term \\ then \: t _{n} < 0 \implies \: a + (n - 1)d < 0 \\ \implies \: 24 + (n - 1) \times - 3 < 0 \\ \implies(27 - 3n) < 0 \implies27 < 3n \\ \implies3n > 27 \\ \implies \: n > 9 \\ \therefore \: n = 10 \\ hence \: first \: negative \: term \:is \: 10$