Question

4th term of an arithmetic sequence is 1/5 and 5" term is 1/4, then what is its 20"
term.
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Answer 1

1. t4=1/5 tn=a+(n-1)d
2. t5=1/4=a+4d=1/4

a+3d=a+4d=1/5=1/4

a-a=4d-3d=1/5=1/4

d=1/20