Answer:
b1 = 2 ; r = 3
Step-by-step explanation:
Given that :
if b3 −b1 = 16 and b5 −b3 = 144.
For a geometric series :
Ist term = a
Second term = ar
3rd term = ar^2
4th term = ar^3
5th term = ar^4 ;...
If b3 - b1 = 16;
ar^2 - a = 16
a(r^2 - 1) = 16 - - - (1)
b5 - b3 = 144
ar^4 - ar^2 = 144
ar^2(r^2 - 1) = 144 - - - - (2)
Divide (1) by (2)
a(r^2 - 1) / ar^2(r^2 - 1) = 16 /144
a / ar^2 = 1 / 9
ar^2 = 9a
Substitute for a in ar^2 - a = 16
9a - a = 16
8a = 16
a = 2
From ar^2 - a = 16
2r^2 - 2 = 16
2r^2 = 16 + 2
2r^2 = 18
r^2 = 18 / 2
r^2 = 9
r = √9
r = 3
Hence ;
a = b1 = 2 ; r = 3
Answer:
100pi
Step-by-step explanation:
pi5^5=25pi
2*2=4
25pi*4=100pi
