How can I graph quadratic or quartic equations

[Guest]

I want to know how can I graph equations from linear equations to quartic or
higher degree equations using excel charts utility?

 

[David Biddulph]

Decide your expression(s) for Y as a function of X.
Put a range of X values in the first column, & calculate the corresponding Y
values in the next column (and in the third & subsequent columns if you've
got more than one equation that you want to plot together).
Select the two (or more) columns.
Insert/ Chart/ XY Scatter.

 

[Guest]

Thanks Mr. D. Biddulph. Thanks very much. When I posted my question I had
already done what you instructed, but the resulting curve was not acurated.
At least not even remotely alike the one resulting in a graphic calculator as
the TI-83. Even though the resulting values of f(x) were correct. That was
the reason why I did asked my question. Do you know another method to do it
more acurately.

 

[Jon Peltier]

Did you use appropriate significant digits in your coefficients? Probably,
if the calculated Y values are accurate, as you state.

Did you make an XY chart? A Line chart will not portray X values accurately,
and this is the most common reason for people to get inaccurate charts.

- Jon

 

[Guest]

Thanks Mr. Peltier. Yes I made an XY chart using curve lines... and the
digits in my coefficients were correct. I think I did everything ok. I mean
I calculated the values of f(x) for each value of x in a range -10 to +10.
The resulting values were exact... Then I did <Insert, Object,Chart,
Scatter...> and the resulting graph wasn't even remotely alike the one that
you get in the graphic calculator. Thanks anyway...

 

[Mike Middleton]

raidven -

I don't understand.

If you already have an XY (Scatter) chart with correct results, why are you
choosing Insert | Object | Microsoft Graph Chart | ... ?

- Mike
http://www.mikemiddleton.com

 

[Jon Peltier]

Strange, I don't see the reply.

There might be a difference in the algorithms used to generate the smoothed
curve. I avoid smoothed lines in charts whenever possible, because they can
give a false sense of where the function goes.

Another point, how do you know the graphing calculator is accurate?

- Jon