Need help entering problems into my ti-83

[platinumike]

This is for calculus.We're on the subject of limits and I cant get any right answeres when entering theese problems into my calculator, I particularly have problems when it invovles asking the square root of something. like the square root of x+3 for example. I'm assuming i would use the radicand symbol then x then hit + and hit radicand 3?. The particular problem im having trouble with is:

<radicand>x+6</radicand>-4 / x-10

as x approaches 10

the answer to this if you managed to actually read it is 1/8. However i get something completely different.

 

[hypn0tik]

Originally posted by: platinumike
This is for calculus.We're on the subject of limits and I cant get any right answeres when entering theese problems into my calculator, I particularly have problems when it invovles asking the square root of something. like the square root of x+3 for example. I'm assuming i would use the radicand symbol then x then hit + and hit radicand 3?. The particular problem im having trouble with is:

<radicand>x+6</radicand>-4 / x-10

as x approaches 10

the answer to this if you managed to actually read it is 1/8. However i get something completely different.

No! sqrt (x + 3) is NOT the same as sqrt (x) + sqrt (3).

Try using brackets instead.

Edit: For your specific problem, you need to enter it in this format:

(sqrt(x+6))/(x-10)

 

[Tu13erhead]

Hmm...lets see if I can remember how to use the ol' TI-83.

Assume "sqrt" means the radical.

Press the "Y=" button in the top left. Under Y1, enter "sqrt(x+6)-4/x-10". Might need to use parenthesis as necessary. Then you can either press the Table button and scroll to 10 or Graph and move the cursor to x = 10.

Does that help?

 

[KillerCharlie]

Did you put parenthesis around the x+6? It should be like <root>(x+6)</root>. Otherwise if you type <root>x+6</root> it actually interprets it as root(6) + 3.

Solution: buy a ti-89, especially if you're an engineer

 

[cirthix]

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[platinumike]

Thanks alot for the replies but im not getting anything anywhere near 1/8th. Im getting numbers like 389. Im reading my book and what i think it involves is rationalizing the numerator, but im still stuck on trying to do that.