Question

Find the 17th term from the end of the ap 1,6,11,16... 211,216

Answer 1

here
first term =1
common difference=6-1=5
now,
use formula ,
tn=a+(n-1) d
216 =1+(n-1) 5
215/5=n-1
n=44

hence 44 terms in this series
so, from last 17th term=from first (44-17+1) th term = 28th term from first

now,
28th term=a+(28-1) d
​​​​​
=1+27 x 5 =136


So 17th term from end is 136

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