Question

I want arhemetic progression a-18.9 d2.5 n an 3.6 what is n

Answer 1

RIGHT QUESTION :

[Q] First term of an A.P is 18.9 and Common difference is 2.5. nth term of this A.P is 3.6. Find number of terms in this A.P.

Answer:

$\huge{\pink{\green{\sf{\therefore n=10}}}}$

Step-by-step explanation:

$\huge{\pink{\green{\underline{\red{\sf{SOLUTION-}}}}}}$

▪In the give question information is given about an A.P whose first and last term is given and common difference is given.

▪We have to find Number of terms in this A.P.

▪According to given question :

$\underline \bold{ Given : } \\ \implies a = - 18.9 \\ \implies d = 2.5 \\ \implies a_{n} = 3.6 \\ \\ \underline \bold{To \: Find : } \\ \implies nth \: term = ?$

▪We know formula for nth term of an A.P.

▪Putting all values in that formula for finding Number of terms.

$\implies a_{n} = a + (n - 1)d \\ \implies 3.6 = - 18.9 + (n - 1) \times 2.5 \\ \implies 3.6 + 18.9 = (n - 1) \times 2.5 \\ \implies \frac{22.5}{2.5} = n - 1 \\ \implies n = 9 + 1\\ \bold{\implies n = 10}$

_________________________________________

Answer 2

Explanation:-

$a_n = 3.6$

$a = -18.9$

$d = 2.5$

To find :-

The value of n.

• By using n th term formula :-

$\boxed{a_n = a + (n-1)d}$

• put the given value .

→$3.6 = -18.9 + ( n-1)2.5$

→$3.6= -18.9 + 2.5n -2.5$

→$3.6 = -21.4+2.5n$

→$3.6 + 21.4 = 2.5 n$

→$25 = 2.5n$

→$n = \dfrac{25}{2.5}$

→$n = 10$

hence,

The value of n is 10.