Answer: Choice D 
Reason:
Exponential functions have the variable in the exponent.
Choice A is a polynomial, which means we can rule it out. Choice B is a log function, so we can rule it out also.
Choice C is a rational function because it is a ratio of two polynomials. This rules out choice C.
Choice D is the only function with the variable in the exponent. That is assuming you meant to say instead of 
Answer:
(9 × 3x+7) - (5 × x+2)
Step-by-step explanation:
Red area
9 × 3x + 7
white area
5 × x+2
Error is between steps 4 and 5. It should say:
Step 4: -9x < 27
Now divide by -9
Step 5: x > -3
Note that the inequality changes direction.
When you mean multiply or divide an inequality by a negative number, the inequality changes direction.
For example:
4 < 5
Multiply by -1:
-4 > -5
Another example:
-5 < 0
5 > 0
