My Math Forum  

Go Back   My Math Forum > High School Math Forum > Algebra

Algebra Pre-Algebra and Basic Algebra Math Forum


Reply
 
LinkBack Thread Tools Display Modes
May 5th, 2010, 04:30 AM   #1
Senior Member
 
Joined: Mar 2010
From: Melbourne

Posts: 178
Thanks: 0

Plotting

Hi,

I have two functions:

y = 1/5 (4x -3)

and its inverse function:

y = 5x+3/4

--

How do I plot and represent these on an xy graph ?

wulfgarpro.
wulfgarpro is offline  
 
May 5th, 2010, 05:28 AM   #2
Global Moderator
 
The Chaz's Avatar
 
Joined: Nov 2009
From: Northwest Arkansas

Posts: 2,766
Thanks: 4

Re: Plotting

I prefer to start with the equations in "slope-intercept form" (i.e. "y = mx + b").
Consider the equation y = (3/4)x + (-5)
The slope is 3/4. This means that a vertical increase of 3 units corresponds to a horizontal increase of 4 units. ("rise over run")
The y-intercept is (-5). You can find this directly by evaluating when x = 0...

Step 1: Plot the y-intercept. In this case, we go down 5 units from the origin and mark the point (0, -5).
Step 2: Use the SLOPE to get from this point to another point, and then from your new point to another, and so on.
So from (0,-5), we go UP 3 and RIGHT 4 units. Up 3 to (0,-2) and right 4 to (4,-2)
(4, -2) is another point on the line. At this point you can draw the line containing the two points and you're done.

Another method is to use the intercepts.
Let's look at your "inverse" equation y = 5x + 3/4
When x = 0, y = 3/4
When y = 0, 5x = -3/4, so x = -3/20.

This information can be consolidated to the two points:
(0,3/4) and
(-3/20, 0).
Plot these points. Draw the line containing them. Boom.
The Chaz is offline  
Reply

  My Math Forum > High School Math Forum > Algebra

Tags
plotting



Thread Tools
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Plotting advanced graphs benmuskler Algebra 1 September 28th, 2013 03:23 PM
Need help with plotting these coordinates uperkurk Elementary Math 1 January 25th, 2012 02:55 PM
Plotting in C++ mathsissmart Computer Science 2 August 26th, 2011 09:55 AM
Box Plotting Software Matt Sullivan Math Software 2 January 4th, 2011 06:13 AM
Data Plotting Help TranzRail New Users 6 October 8th, 2009 06:43 PM





Copyright © 2019 My Math Forum. All rights reserved.