SOLUTION: here's my question- I need to make a graph and state domain and range of function for f(x) = 0.2e^-5x I'm not really sure where to start.

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: here's my question- I need to make a graph and state domain and range of function for f(x) = 0.2e^-5x I'm not really sure where to start.      Log On


   



Question 212755: here's my question- I need to make a graph and state domain and range of function for f(x) = 0.2e^-5x I'm not really sure where to start.
Answer by rapaljer(4671) About Me  (Show Source):
You can put this solution on YOUR website!
Do you mean f(x) = 0.2e^x - 5x? If so, then the domain is easy--there are NO RESTRICTIONS on x (in other words, you can use ANY value of x !), so the Domain is ALL REAL NUMBERS!!

Range is another problem! You will need either a graphing calculator or knowledge of calculus to determine the minimum value of f(x). Also, you will need to notice that as x approaches infinity, f(x) also approaches infinity. As x approaches negative infinity, f(x) approaches + infinity.

Using the algebra.com calculator:
graph%28300%2C300%2C+-10%2C10%2C-15%2C10%2C+.2e%5Ex-5x%29+

See also this graph
graph%28300%2C300%2C+-2%2C4%2C-15%2C5%2C+.2e%5Ex-5x%29+

According to the graph, it appears that the minimum value of the function is approximately -11. Using calculus, I was able to determine that the minimum value is exactly -10. If you are into calculus, send me an Email and I can show my work on this.

Range: [ -10, + infinity)

R^2

Dr. Robert J. Rapalje
Seminole Community College
Altamonte Springs Campus
Florida