Question

find the 8th and 10th term of g.p whose first term and common ratio are 6and2 respectively

Answer 1

Step-by-step explanation:

Given that:-

First term of G.P. (a)=25

Last term of G.P. (n)=

625

1

As we know that, n

th

term of a G.P. is given by-

a

n

=ar

n−1

625

1

=25×r

n−1

⇒r

n

=

15625

r

.....(1)

Sum of G.P. =

625

19531

[Given]

Sum of n terms of G.P.-

S

n

=

r−1

a(1−r

n

)

[∵r<1]

∴

1−r

25(1−

15625

r

)

=

625

19531

⇒15625−r=19531−19531r

⇒19530r=19531−15625

⇒r=

19530

3906

=

5

1

Hence the common ratio of the given G.P. is

5

1

.

Answer 2

Answer:

Step-by-step explanation:

Tn =ar n-1

To find the 8th term of a g.p

T8 = 6×{2} 8-1

= 6×{2} 7

=768

To find the 10th term of a g.p

T10 =6×{2} 10-1

=6×{2} 9

=3072