ARITHEMATIC PROGRESSION

Asked by chahat | 11th Mar, 2009, 12:29: AM

Expert Answer:

Let the first term is a and common diff is d

so the nth term is given by

nth term =a+(n-1)d

Acc to question,

a+18d=3[a+5d]

2a=3d

a=3/2(d..).(i)

Next,

9th term =19(given)

So,

a+8d=19

(3/2)(d)+8d=19

(3d+16d)/2=19

d=2

a=3/2(d)=3

a=3

now, with a and d  known, you can easily find the A.P.

Answered by  | 11th Mar, 2009, 09:51: AM

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