# Homework Help: Equations - Graphs

1. Nov 3, 2009

### DarkPhoenix

1. The problem statement, all variables and given/known data

I have been given this equation : 4/5 X 2^x
I have drawn the graph.

Now, I was asked to draw the graph of y = 8 – 2x by using the 1st equation above.

Can you help me in doing so? I know that the 1st Co-ordinates is (0,8) how can I find the other co-ordinate to draw the line?

2. Nov 3, 2009

### n!kofeyn

There isn't any need to use that graph to graph y=8-2x. This is just a line. Plot two points. Then draw a line through them.

Also, don't use X for multiplication. Ever. :)

3. Nov 3, 2009

### LCKurtz

What you have written isn't an equation; there is no = sign. And it also isn't clear what it means. Is the X supposed to be multiplication? Is it supposed to be (4/5)2x? Where is the y?

4. Nov 3, 2009

### Staff: Mentor

The only way this problem makes any sense is if the second equation is y = 8 - 2x. In that case, you can look at the graph of this equation as being some transformations of the graph of y = (4/5)2x.

5. Nov 3, 2009

### DarkPhoenix

Sorry the 1st equation was y= (4/5)2^x

The 1st Co-ordinates are (0,8) since the y-intercept is 8 but I don't know how to find the 2nd Coordinates (x,y)

6. Nov 3, 2009

### Staff: Mentor

What about the second equation? Is it y = 8 - 2x or y = 8 - 2x?

7. Nov 3, 2009

Good catch.

8. Nov 3, 2009

### DarkPhoenix

The 2nd equation is y = 8 - 2x

9. Nov 3, 2009

### Staff: Mentor

Then this problem makes no sense.