Question

The last term of G.P. is 64, common ratio is 2
and sum of n terms is 127. Find the number of
terms.

​

Answer 1

Answer:

Given T

n

=ar

n−1

=128,r=2

S

n

=

r−1

a(r

n

−1)

=255 or

r−1

ar

n−1

.r−a

=255 or

2−1

128.2−a

=255

∴256−255=a or a=1.

Now ar

n−1

=128

∴1.(2)

n−1

=2

7

∴n−1=7orn=8.

Step-by-step explanation:

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Answer 2

Answer:

7The last term of G.P. is 64, common ratio is 2 and sum of n terms is 127. Find the number of terms.