Saxon Calculus and Hp49+



#2

Can anyone help? My son who is 15 is trying to learn Calculus at home. Now he also has the challenge of learning to use the HP 49+ graphing calculator. He has used the HP-15 in the past. The book called for TI-83, but we couldn't bear to buy a TI having been an HP RPN family for 30 years.


The problem

Use a graphing calculator to approximate the values of y
when x = pi and when x = Square root of 2

Given: y = (square root of x + one) over x


Stacey Bower and John


#3

It is pretty much like hte 48 series. You write the expression and save it to a variable, and then you can manipulate it. I think the manual should help you to know what buttons to push, but that is the basic gist of it.

#4

Hi:
Sorry to say this but go for a TI 89. TI is a LOT more education oriented than HP. I am an HP fan but I recognize that on that subject TI are a lot better than HP

Br,

#5

Congrats on your boy taking calculus at 15, brighter than I was at his age!

There are many ways to do this on the 49/49+. This is one way:

Enter the Equation Writer with the EQW key. You are now in a special screen environment allowing you to write any equation or expression exactly as you would on paper. Type in your function: Y(X)=(square root of X + one) over X. Enter the equation onto the stack, you will see it on level one. Type DEFINE, the level one entry disappears. Hit the VAR key, you will see Y displayed. To see the expression in terms of X, hit the X key, then the F key under the variable Y key. You will now see (square root of X + one) over X displayed. As a number example, hit 1 then the F key under the variable Y key and you get square root (2). For numeric approximations go RightShift ENTER. When you're through with that definition type 'Y' PURGE to delete it.

Edited: 15 Sept 2005, 1:30 p.m.


#6

Thank you, Claudius for prescribing a way to solve the problem!

We were wondering if you could tell us how after entering the equation we can solve for any number of particular x variables by imputting the x variable value.

Then the calculator will give the corresponding y value and mark it on the graph.

S & J


#7

Speaking as another underage calculus student, I can say the 49g+ is fine for the purpose. TI just has better marketing.

Use the left-shift-hold and F1 keystroke to get to the Y= editor that lets you manage multiple functions. The add softkey will call the equation writer and give you a Y1= blank. From here you type in the function and hit enter. The functions are automatically stored to the proper variables (after you graph them or hit the OK softkey.) Once you have graphed the functions, the f(x) softkey in one of the menus will get you the y value, and leave it on the stack. For multiple values, you can use the table and type in your own values. The same menu with the f(x) button also can show you f' and graph the tangent line where the cursor is.

#8

I think you want to plot or table this function and then get values?

The 48/49/49+ create plot variables when plots are created. A neat way to keep these variables from cluttering up the Home Directory is to create a new directory for your plots. Type Plot then the command CRDIR. You will see a newly created directory named Plot. Press the F key under the Plot name and you enter this new directory. All the variables will be blank at this time. To delete any EQ, PPAR, ZPAR variables, enter them on the stack and type PURGE. To exit this directory use the commands UPDIR or HOME.

There are many ways to create plots, using (hold) Left-Shift (Y= or GRAPH) and the manual does a pretty decent job of describing this. You can also access the old 48 plot menu by typing 81. MENU , if you have the soft menu flag 117 set, -117 SF

You can also easily create a table of values for the function using the (hold) Left Shift TABLE function. This may the best way of getting what you want. I realize I'm not guiding you step by step and I apologize, I'm just very busy at the moment.

Edited: 15 Sept 2005, 11:11 p.m.

#9

"Use a graphing calculator to approximate the values of y when x = pi and when x = Square root of 2

Given: y = (square root of x + one) over x"

---------

All the responses I've seen so far assume you are trying to find EXACT values of y for those two specific values of x. I think the intent of the problem is to GRAPH the function over a reasonable interval and then DIGITIZE approximate y values from the graph.

--Mark


#10

To plot a function on the 49G+, do the following:

  1. Go to the "Plot Functions" menu (APPS->enter)
  2. Press enter again to select the first item "Equation Entry."
  3. Enter the equation as per the example above, but only the right hand side. (i.e. no "y(x)=")
  4. Press the DRAW soft key when you are finished entering the equation. This will plot the function using the default axes and tick values.
  5. You can now use the arrow keys to move a cursor around the graph.
  6. When you are near a point you would like to see the x and y values for, press the "(X,Y)" softkey.
  7. Press ON (cancel in this context) twice to return to the stack display

Hope this helps.


#11

Quote:
To plot a function on the 49G+, do the following:

1.Go to the "Plot Functions" menu (APPS->enter)
2.Press enter again to select the first item "Equation Entry."
3.Enter the equation as per the example above, but only the right hand side. (i.e. no "y(x)=")
4.Press the DRAW soft key when you are finished entering the equation. This will plot the function using the default axes and tick values.
5.You can now use the arrow keys to move a cursor around the graph.
6.When you are near a point you would like to see the x and y values for, press the "(X,Y)" softkey.


Does the 49 include the TRACE function? On the 48, pressing the TRACE softkey and then the (X,Y) softkey will keep the cursor locked onto the graphed line. The left and right cursor keys will cause the cursor to follow the line in the -X or +X directions and the X and Y positions of the cursor will be displayed continuously at the bottom as the cursor moves. That makes it simple to move to a particular X value and see the corresponding Y value.


#12

Quote:

Does the 49 include the TRACE function? On the 48, pressing the TRACE softkey and then the (X,Y) softkey will keep the cursor locked onto the graphed line. The left and right cursor keys will cause the cursor to follow the line in the -X or +X directions and the X and Y positions of the cursor will be displayed continuously at the bottom as the cursor moves. That makes it simple to move to a particular X value and see the corresponding Y value.


Yes, it works exactly the same in the 49G+ instead of manually moving the cursor around as in my example, you can use the TRACE function as you describe.

I thought there was some requirement to "guesstimate" the values, though.


#13

I am the son currently doing the Calculus. Thanks for the help, but what I really want to know how to do is: After I have graphed the function, can I imput values of x (i.e. pi or square root of 2) and have the calculator plot the matching y value? My textbook tells me how I can do it on a TI-83, but many of the buttons aren't carried over in exactly the same way. Thanks much.

John


#14

If you are having difficulty, you might consider an Hp39G. It is a near Ti-83 clone and can be found on ebay for about $30 (NEW old stock) for the following reasons:

Unconventional Rubber buttons
Ti-83 clone ie Algebraic only (very similar keyboard layout and press sequence).
Slow (in comparision to a Ti-83).

On the plus side, it is cheap and it has a lot more math, calculus functions and memory over a Ti-83/84.

The newer Hp39G+ is basically an upgraded hardware version similar to your Hp49G+ in feel and speed. About $90 retail.

Or you might find a Ti-83/84 used at a local college or pawn shop.


I would still suggest keeping and learning your Hp49G as it is truly far superior to the Ti-83. But learning how to use and master an Hp49G will take months (and/or years depending upon HOW well you want to know it), not days or weeks, and you probably do not have that luxuary.


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