Graphing functions and identifying features

Keep up the good work.In summary, the conversation discusses two graphs, y=e^-2x-1 and y=ln(x-2)+1, and the person is seeking guidance on how to approach graphing them. It is recommended to familiarize oneself with the graphs of y=e^x and y=ln(x), and to use knowledge of shifting and stretching graphs. The person also mentions a lack of confidence in this aspect of math and apologizes for bothering. They thank the expert for their guidance.
  • #1
zebra1707
107
0

Homework Statement



Hi there

I need assistance with two graphs that are causing me some problems

y=e(^-2x)(-1) and y=ln(x-2)+1

Homework Equations



I just need some guidence as to where to start - starting with a table - what range is approriate?

The Attempt at a Solution



Stuck
 
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  • #2
[itex]e^x[/itex] goes to 0 very rapidly for x< 0 and goes up very rapidly for x> 0. I would recommend taking x from -1 or -2 to +4 or +5.

ln(x) is only defined for x> 0 so ln(x- 2) is only defined for x> 2. I would recommend taking x from 2 up to, say 10.

Wouldn't it have been faster to just play around with some numbers rather than wait for someone to respond here? Do you not have a graphing calculator? It would have taken only a few seconds to try various value on a calculator.
 
  • #3
zebra1707 said:

Homework Statement



Hi there

I need assistance with two graphs that are causing me some problems

y=e(^-2x)(-1) and y=ln(x-2)+1

Homework Equations



I just need some guidance as to where to start - starting with a table - what range is appropriate?

The Attempt at a Solution



Stuck
I assume you mean [itex]\displaystyle y=(-1)e^{-2x}\,,[/itex] which you could write as y = (e^(-2x))(-1), (the location of parentheses is important) or y = -e^(-2x), or better yet, y = -e-2x,

and y = ln(x-2) + 1 .

Are you familiar with the graphs of:
[itex]\displaystyle y=e^{x}\,,[/itex]​
and
[itex]\displaystyle y=\ln(x)\ ?[/itex]​
That's the place to start.

Then use what you've (hopefully) been learning about shifting, stretching, shrinking, flipping, etc. graphs.
 
  • #4
HallsofIvy said:
[itex]e^x[/itex] goes to 0 very rapidly for x< 0 and goes up very rapidly for x> 0. I would recommend taking x from -1 or -2 to +4 or +5.

ln(x) is only defined for x> 0 so ln(x- 2) is only defined for x> 2. I would recommend taking x from 2 up to, say 10.

Wouldn't it have been faster to just play around with some numbers rather than wait for someone to respond here? Do you not have a graphing calculator? It would have taken only a few seconds to try various value on a calculator.

Thank you, yes, you are right. I think just a lack of confidence in this aspect of Maths. Sorry to be a bother. Regards
 
  • #5
SammyS said:
I assume you mean [itex]\displaystyle y=(-1)e^{-2x}\,,[/itex] which you could write as y = (e^(-2x))(-1), (the location of parentheses is important) or y = -e^(-2x), or better yet, y = -e-2x,

and y = ln(x-2) + 1 .

Are you familiar with the graphs of:
[itex]\displaystyle y=e^{x}\,,[/itex]​
and
[itex]\displaystyle y=\ln(x)\ ?[/itex]​
That's the place to start.

Then use what you've (hopefully) been learning about shifting, stretching, shrinking, flipping, etc. graphs.

Many thanks, I appreciate the guidance.
 

1. What is the purpose of graphing functions?

The purpose of graphing functions is to visually represent the relationship between two or more variables. This allows us to better understand the behavior and patterns of the function and make predictions about its behavior in different scenarios.

2. What are the basic features of a function that can be identified on a graph?

The basic features of a function that can be identified on a graph include the x and y intercepts, the slope, the maximum and minimum points (if applicable), and any points of symmetry or discontinuity.

3. How do I determine the domain and range of a function from its graph?

The domain of a function is the set of all possible input values, which can be determined by looking at the horizontal extent of the graph. The range of a function is the set of all possible output values, which can be determined by looking at the vertical extent of the graph.

4. What is the difference between a linear and a non-linear function, and how can I identify them on a graph?

A linear function has a constant rate of change, meaning its graph is a straight line. A non-linear function does not have a constant rate of change and its graph can take on various shapes, such as curves or loops. To identify them on a graph, you can look at the overall shape of the curve or use the slope formula to determine if the function is linear or non-linear.

5. Can I use a graph to solve equations or find the roots of a function?

Yes, a graph can be a useful tool in solving equations or finding the roots of a function. The x-intercepts of a function's graph represent the solutions to the equation y=0 and the points where the graph crosses the x-axis are the roots of the function. However, it is important to note that sometimes the roots may not be visible on the graph and other methods may be needed to find them.

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