Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • NCERT
  • Find the number of terms in each of the following APs : (i) 18, 15 1/2, 13, ..., -47

Q : 5     Find the number of terms in each of the following APs :

             (ii)   \small 18,15\frac{1}{2},13,...,-47

Answers (1)

best_answer

Given AP series is 
\small 18,15\frac{1}{2},13,...,-47
suppose there are n terms in given AP
Then, 
a = 18 , a_n = -47
And 
d= a_2-a_1 = \frac{31}{2}-18 = \frac{31-36}{2} = -\frac{5}{2}
Now, we know that
a_n =a + (n-1)d
\Rightarrow -47=18 + (n-1)\left ( -\frac{5}{2} \right )
\Rightarrow -47-18= -\frac{5n}{2}+\frac{5}{2}
\Rightarrow -\frac{5n}{2}= -65-\frac{5}{2}
\Rightarrow -\frac{5n}{2}= -\frac{135}{2}
\Rightarrow n = 27
Therefore, there are 27 terms in given AP

Posted by

Gautam harsolia

View full answer

Similar Questions

Trending Articles/News

anam-khan

CBSE Class 10 Hindi Exam Analysis 2025: Paper ‘well-organised, moderately difficult'; MCQ section easy
anam-khan

No change in CBSE Class 10 subjects for 2026, board will offer 45 languages: Chairman clarifies
anam-khan

Minister objects to Punjabi's absence from list in CBSE draft; board says language list 'indicative'

Latest Question