Question

The 5th term of a GP is -48 and the 7th term is -12 .Find the first term and the common ratio of the GP?If you don't know kindly don't answer ​

Answer 1

Answer:

T5= a+ 4d= -48. i

T7= a+6d= -12. ii

i-ii

d= 18

putting the value in (i)

a= -120

Answer 2

Answer:

Step-by-step explanation

Let  the first term be a  and the common ratio be r

as we know that

nth term = $ar^{n-1}$

So,

5 th term = $ar^{4}$  = -48                -  (1)

7 th term = $ar^{6}$ = -12                 -   (2)

dividing 2 by 1 we get

$r^{2}$ = 1/4

r= +1/2 or -1/2

putting value of r in (i)

we get a = -48 x 16 = -768

Hence

first term= -768

common ratio = +1/2 or -1/2