Here's the question you clicked on:
burhan101
Restriction for logs
|dw:1358467325462:dw|
Now how do i find the restriction(s) for this ? :S
The thing in the bracket may not be less or equal to zero.
it's only supposed to be x>2
i dont understand why
because the x has to satisfy both x>-5 and x>2, but since the has to be greater than 2, it can't fall between -5 and 2, because then the equation would be undefined
Think about it this way: The two restrictions must be met. Meaning, the number must be greater than 2 AND it must be greater than -5. But, if it is greater than 2, it is greater than -5! So, the greater than -5 is dominated by the greater than 2 restriction. Therefore the only restriction is greater than 2
but cant there be more than one restriction ? :S
There can. for instance, it it was log(-x + 7) + log(x+2), the restrictions would be -x + 7 > 0 AND x + 2 > 0 so, it's x< 7 AND x> -2 which reduces to: -2 < x < 7