The 2nd and 5th term of a geometric progression are - 6 & 48 find the sum of the first four term respectively

Answer 1

a+d = -6
a+4d = 48
so,
3d=54
d=18
so, a=-24
and the sequence is

-24 -6 12 30 48 ...

Answer 2

I think this method is for a. P, not gp

Answer 3

I think this method is for a. P, not gp
The correct one is
ar=-6
ar^4=48
r^3=-8
So r=-2
Sn=a(1-r^n)
- - - - - - - -
1-r
S4=3(1-(-2^4)
- - - - - - - -
1-(-2)
S4=3(1-16)
- - - - -
1+2
S4=3(-15)
- - - - -
3
S4=-15
That's the correct answer.