graph parabola (positivre& Negative numbers)

[barbara.schlachter]

Help. I want to know how to graph a parabola. I need an
x axis (-5 to 5) and a y axis ( -5 to 5). y = x^2 +x +2

Thanks

 

[jeff]

Hi,

Homework? Since you need both X and Y values, you know
that Y depends on X. So first start your column of X
values (-5 to 5) (say, in column A);

In B, you'll put your Y values which are calc'd from
the formula =x^2+x+2; put this in first Y cell and copy
down;

Now youhave your X's and Y's; goto INsert==chart==
select line and off you go!

jeff

 

[BenjieLop]

*Help. I want to know how to graph a parabola. I need an
x axis (-5 to 5) and a y axis ( -5 to 5). y = x^2 +x +2

Thanks *

On Cell A1, enter -5
On Cell A2, enter the formula =(A1+1)
Copy down the formula in Cell A2 until you get to your desired maximu
value of 5 (this will be Cell A11)

On Cell B1, enter =(A1^2 + A1 + 2)
Copy down this formula until you get to Cell B11

Highlight the range A1:B11

Click on the chart wizard/XY (Scatter)

From here, you can click on "Finish" to see how the graph looks like
Otherwise, you can go to "Next" and get to dress up the graph anywa
you want to.

BTW, the only values you need to graph this function are the x-value
(which you are plugging in Column A). Since y=f(x), you do not need t
look for "-5 to 5" in the y-axis

 

[J Brydle]

The other replies cover how to get the graph, but so far not how to make it
-5 to 5 in both directions. When you have your chart showing in the
worksheet, double click on the set of numbers (along either axis, you'll need
to do it for each) and go to the "Scale" tab. You can change the minimum and
maximum values to -5 and 5. If you don't manually change them, Excel will
pick them for you and you'll end up with -5 to 5 in the X direction (or maybe
-6 to 6 just to have some space on the sides) and something like 0 to 35 in
the Y direction. It does this because that includes all of the data, but if
you change it to be -5 to 5 in both directions you will lose some of the
graph, because 5^2+5+2 is of course 32, and out of the range. Plus there are
no negative Y values in that formula so the bottom half of the graph wil be
empty. You'll only see the bottom of the parabola at the top of the graph,
but if thats the range you need, then so be it.