- #1
LiHJ
- 43
- 2
Homework Statement
Dear Mentors and Helpers,
here's the question:
Find the range of validity for (1 + 3x/2)^(-1) and (1 + 1/(3x))^(-1).
Homework Equations
The Attempt at a Solution
For the first binomial series:
-1 < 3x/2 < 1
-2 < 3x < 2 (multiply 2 throughout)
-2/3 < x < 2/3 (divide by 3 throughout)
For the second binomial series:
-1 < 1/(3x) < 1
-3x < 1 < 3x (multiply 3x throughout)
-3x < 1 or 1 < 3x
x > -1/3 (divide -3, inequality change sign) or 1/3 < x (divdide 3)
Therefore I get: x > -1/3 or x > 1/3
However my range isn't correct for the second binomial series can any Mentors or PF helper guide me and correct my mistakes.
Thank you