# TI TI Nspire CX CAS How do I input full fractions and 84-Plus mode?

I have been trying to figure out how to plot a differential equation using my TI Nspire with very little luck. I managed to find that I can set the graph of the calculator to a directional field but I am not 100% sure I am getting the right results. So I figured I would ask to see if anyone here uses a TI Nspire and can give me an idea of how to plot these equations.

For example I have the equation

y'=-2y^2
where a solution for it is:
y(t)=3/(6t-11)
with an initial value of:
y(2) = 3

in my TI Nspire I put in something such as:

y1'=−2*y1^(2)

but since I know y(2)=3 what do I do? exactly? Am I doing this right?

I also have another equation where:
y'+4y=cos(t)

a known solution of
y(t) = 4/17cos(t)+1/17sin(t)+Ce^-4t

and initial known value of:
y(0) = -1

should I solve this in terms of y' to plot it or what exactly?

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How do I input full fractions for algebra into the Nspire? Here is a example:

6/8 X 6 4/5 = 5 1/10

When I try to put this in the calculator my answer is 51/10 and not 5 1/10 with a space after the 5. 5 space 1/10.

It only lets me do numerator and denominator but not a whole number beside of it or gives me a whole number X or multiplication symbol beside the numerator and denominator.

I can't find a answer on the internet so far on how to do this.

They talk about TI 84-Plus mode and I don't see a option on how to do it anyplace so far.

Thanks

Hi all,

I know this is very subjective and probably asked a few hundred thousand times. I'm an Mechanical Engineering student looking to upgrade from my ti 83. I know atleast so far my math classes (Calc II) wont allow a CAS capable calculator, and that you can get the interchangable keyboards to remove that function for the NSpire. And as far as I know there is know CAS program for the Prizm. Is the CAS system really that helpful?, I've never had the chance to use it. I know Id use the graphing feature of it a lot and integral/derivative features of them both and program in notes for formulas etc. Is it justifiable to spend another \$50 on the Nspire if I can't use the CAS touchpad keyboard of it?

Thanks guys