Use logarithm.
Did you understand the first line of response #2.I assumed this is a geometric series question and calculated that r = 1/3. U1 also = 1/3. So Un=U1 x rn-1
so 1/100000= 1/3 x (1/3)n-1
1=100000/3 x (1/3)n-1
3n-1= 100000/3
And then I got stuck
Why are you talking about n-1. This makes things more complicated.I assumed this is a geometric series question and calculated that r = 1/3. U1 also = 1/3. So Un=U1 x rn-1
so 1/100000= 1/3 x (1/3)n-1
1=100000/3 x (1/3)n-1
3n-1= 100000/3
And then I got stuck
Why are you talking about n-1. This makes things more complicated.
The 1st term is 1/31
The 2nd term is 1/32
The 3rd term is 1/33
The 4th term is 1/34
Do you see a simple pattern here??
The nth term is 1/3n
Just solve for the smallest n such that 1/3n<10-6=1/106 which is the same as 3n>106.
If you want to continue your way then you should now multiply both sides by 3
ApologiesDid you understand the first line of response #2.