Question 81283
QUESTION:


find the fourth term of a geometric sequence in which a1=-3 and r=7 



ANSWER:


A series of the form,

a1, a1r^1, a1r^2, a1r^3, a1r^4,........... is called a geometric progression.
where a is the first term and r is the common ratio.


nth term of a geometric progression is given by the formula,


 n th term = a1r^(n-1)


here a1 = -3 and   r = 7



so 4 th term = -3 * (7)^(4-1)



==>          = -3 * 7 ^ 3



==>          = -3*343


==>         = -1029



So 4 th term = -1029



Hope you found the explanation useful.



Regards.


Praseena.