Which of the following exponential functions has the following properties?
1. domain {x|all real numbers}
2. range {y|y 0}
3. the y-values decrease as x increases from left to right
4. the graph is an exponential decay
Answer
a. y = (0.4)x- 3
b. y = (0.4)x
c. y = 0.4(5)x
d. y = -(5)x

Question

Which of the following exponential functions has the following properties?
1. domain {x|all real numbers} 
2. range {y|y > 0} 
3. the y-values decrease as x increases from left to right
4. the graph is an exponential decay
Answer
	 a.	y = (0.4)x- 3
	 b.	y = (0.4)x 
 	 c.	y = 0.4(5)x
	 d.	y = -(5)x

anonymous · Answer

By elimination, d is no good, since the range has no positive elements.  c won't do it, since 5^x is a growth function, not a decay function.  a doesn't work, because some of the range is negative.  That leaves b, which meets all the specifications.