t1 is 23 and tn=tn-1 -3
so t2=t1 -3 (here n=2) => 20
t3=t2 -3 => 20-3=17 and so on...
so the series would be less than 3 for every next no. i.e.
t2=20; t3=17 and so on....so the value i.e. -4 would be for t10. if you go on subtracting every time 3 from the previous no. you would get it as term 10.
Amit
GPREP1, Arithmatic Sequence
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sumithshah
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Simpler way, Use AP formula
Nth term = a + (n-1)*d
V, a = 1st term
N = the number of term you are looking for ( it you are looking for 9th term, N=9)
D = difference between two subsequent term ( in increasing order : so basically the {(nth term) - (n-1)th term}
For this particular one, we get
-4 = 23 + (n-1)*-4
solve n = 10;
Nth term = a + (n-1)*d
V, a = 1st term
N = the number of term you are looking for ( it you are looking for 9th term, N=9)
D = difference between two subsequent term ( in increasing order : so basically the {(nth term) - (n-1)th term}
For this particular one, we get
-4 = 23 + (n-1)*-4
solve n = 10;
