- #1
c.teixeira
- 42
- 0
hi there!
If ab > 0, then (a > 0 and b > 0) or (a < 0 and b < 0). This statement I can prove, just with the basic properties of numbers!
Then, 1[itex]/[/itex]b is defined as b[itex]^{-1}[/itex] right?
So, how does one prove that if [itex]\frac{a}{b}[/itex] > 0, then (a > 0 and b > 0) or (a < 0 and b < 0)?
Can you give me the complete proog of that? Thanks!
For example, how does one prove that if [itex]\frac{x+1}{x-1}[/itex] > 0, then
x > 1 or x < -1?
Regards,
If ab > 0, then (a > 0 and b > 0) or (a < 0 and b < 0). This statement I can prove, just with the basic properties of numbers!
Then, 1[itex]/[/itex]b is defined as b[itex]^{-1}[/itex] right?
So, how does one prove that if [itex]\frac{a}{b}[/itex] > 0, then (a > 0 and b > 0) or (a < 0 and b < 0)?
Can you give me the complete proog of that? Thanks!
For example, how does one prove that if [itex]\frac{x+1}{x-1}[/itex] > 0, then
x > 1 or x < -1?
Regards,