IN AN AP, THE FIRST TERM IS 8, nTH TERM IS 33 AND SUM OF FIRST n TERMS IS 123, FIND n AND d.

Asked by  | 22nd Feb, 2013, 08:52: PM

Expert Answer:

first term=a=8

 nth term=l=33

 sum to first n terms=Sn=123

Sn=[n(a+l)]2

123=n(41)/2

n=6

l=a+[n-1]d

33=8+5d

d=5

Answered by  | 22nd Feb, 2013, 09:32: PM

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