Question

Which term of the ap 21 18 15 is -81 also is any term 0 give reason for your answer?

Answer 1

Here's ur answer dear.

The answer is absolutely right.

Answer 2

${ \huge{ \bold{ \underline{ \underline{ \orange{Question:-}}}}}}$

Which term of the ap 21 18 15 is -81 also is any term 0.. Give reason for your answer?

_______________

${ \huge{ \bold{ \underline{ \underline{ \purple{Answer:-}}}}}}$

✒Given : -

• A.P. = 21, 18 , 15 ..

✒To Find : -

• Value of n = ?

✒Here : -

• a = 21
• d = -3
• $\sf{{a}_{n}}$ = -81

${ \large{ \bold{ \underline{ \underline{ \blue{According\:to\:the\:Question:-}}}}}}$

$\dashrightarrow\sf{{a}_{n}=a+(n-1)\:d}$

$\dashrightarrow\sf{-81=21+(n-1)\:(-3)}$

$\dashrightarrow\sf{-81=24-3n}$

$\dashrightarrow\sf{-105=-3n}$

$\leadsto\sf{{ \large{ \boxed{ \bold{ \bold{ \green{n=35}}}}}}}$

⤿Therefore , the 35th term of given AP is -81 ..

✒Now ,

⤳Using $\sf{{a}_{n}}$ = 0

$\dashrightarrow\sf{21+(n-1)\:(-3)=0}$

$\dashrightarrow\sf{3(n-1)=21}$

$\dashrightarrow\sf{3n-3=21}$

$\dashrightarrow\sf{3n=21+3}$

$\dashrightarrow\sf{3n=24}$

$\dashrightarrow\sf{n=\cancel\dfrac{24}{3}}$

$\leadsto\sf{{ \large{ \boxed{ \bold{ \bold{ \green{n=8}}}}}}}$

⤿So , the 8th term is 0 ..