DIRECTIONS for the question:Solve the following question and mark the best possible option.
If fourth term of G.P. is 8 then product of its first seven terms is
A)
85
B)
84
C)
810
D)
87
E)
None of these
D
Let ‘a’ be the first term and ‘r’ be the common ratio. So T4 = ar3 = 8. Now we have product of first seven terms = a× ar × ar2 × ar3 × ar4 × ar5 × ar6 = a7r21 = (ar3)7 = 87.