# Exponential and logarthmic functions

1. Jan 12, 2012

### NeomiXD

1. i) For what values of a with the expression log2a:

a) yield positive numbers?
b) yield negative numbers?
c) yield numbers greater than 1?
d) yield numbers between 0 and 1?
e) be zero?
f) be undefined?

Solution:

1. a) a > 1
b) 0 < a < 1
c) ?
d) ?
e) a = 1
f) a < 0

2. Jan 12, 2012

### Staff: Mentor

a, b, e, and f look fine.
For the other two, it would be helpful to sketch the graph of y = log2x.
(c) For what values of x is y > 1?
(d) For what values of x is y between 0 and 1 (i.e., 0 < y < 1)?

3. Jan 13, 2012

### HallsofIvy

$y= log_2(x)$ is the same as $x= 2^y$.
c) when is $log_2(x)< 0$?
If y< 0 what is $2^y$

d) when is $log_2(x)> 0$?
If y> 0 what is $2^y$?

Last edited by a moderator: Jan 13, 2012
4. Jan 13, 2012

### Redbelly98

Staff Emeritus