Question

The 18th term from end in the series 2,5,8,......,239 is :

Answer 1

Answer:

188 is a right answer and if u like it please give me a BRAINLIEST it

Answer 2

Answer:

The 18th term from end in the series 2,5,8,......,239 is 188.

Step-by-step explanation:

Given A.P

2,5,8,.......,239

First term of this A.P $a_1 = 2$

and second term of this A.P $a_2 = 5$

Common difference

$d = a_2 - a_1 \\ = 5 - 2 \\ = 3$

The nth term of an A.P is given by

$a_n = a_1 + (n - 1)d \\ = 2 + (n - 1) \times 3 \\ = 2 + 3n - 3 \\ = - 1 + 3n.......(1)$

First calculate number of terms (n) in this A.P

put $a_n = 239$ the last term of A.P in above equation (1),

$239 = - 1 + 3n \\ 3n = 239 + 1 \\ 3n = 240 \\ n = \frac{240}{3} \\ n = 80$

Hence this A.P contains 80 terms.

For calculating 18th term from the end means (80-17) th term from starting of A.P

Hence we have to calculate 63th term of this A.P

So put n = 63 in equation (1),

$a_{63} = - 1 + 3 \times 63 \\ = - 1 + 189 \\ = 188$

Hence 18th term of from the end of this A.P series is 188.

Know more about Arithmetic progression:

1) https://brainly.in/question/4219484

2)https://brainly.in/question/2768711