Tereare n terms in an AP. Then, fourth term from the beginning is which term from the last?

Oops! I'm sorry! I mistook your question! This is the correct answer:

first term =  a
common difference = d
fourth term from beginning = a4 
total number of terms = n
4th term from last = a(n - 4)+1 = an-5

eg - 1, 3, 5, 7, 9
3= a​2
from the last, 3 = a(5-2)+1 = a3+1 = a4

  • 2
first term = a
common difference = d
fourth term from beginning = a4 = a + 3d
Last term = an
common difference from last = an-1​ - an =  - d (since an - an-1​ = d)
fourth term from last = an -3d

​Hope u got it :)
 
  • 0
What are you looking for?