Question

Which term of the A.P.- 21, 18 ,15....is -81 ? Also is any term 0 ? Give reason for your answer .​

Answer 1

$\huge \mathfrak \red{answer}$

The given Arithmetic Progression is 21, 18, 15,…,0,….

The first term = a = 21

Now the common difference = d = -3

nth term = 0

We need to find n.

${n}^{th} \: term = a + (n-1)d$

$0 = 21 + (n-1)(-3)$

$⇒ 3(n-1) = 21$

$⇒ n-1 = 7$

$⇒ n = 8$

⇒ The 8th of the given Arithmetic Progression is 0.

$\blue{i \: hope \: it \: helpfull \: for \: you}$