SOLUTION: the 4th term of an arithmetic progression is 7. the 2nd term is (-1). find the first four terms of the sequence.

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Question 1098042: the 4th term of an arithmetic progression is 7. the 2nd term is (-1). find the first four terms of the sequence.
Answer by Jeetbhatt10th(11) About Me  (Show Source):
You can put this solution on YOUR website!
Which class do you study? You don't know so simple question
a4=7=a+(4-1)d__(1)
a2=-1=a+(2-1)d__(2)
Subtracting (2) from (1) we get
7+1=3d-d
8=2d
d=4
=>7=a+3d
=>7=a+12
=>a=-5
A.P.:-5,-1,3,7,...