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June 04, 2024, 10:40:33 am
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Author Topic: TI-89 Titanium question  (Read 688 times)  Share 

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noah the lettuce

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TI-89 Titanium question
« on: January 20, 2014, 05:00:55 pm »
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Not sure if a setting on my calculator or if I'm entering it wrong but every time I try to solve a certain line on my calculator... e.g
Define p(x)=3x^3+kx^2+bx-5
Done
Solve(p(1)=0 and p(-2)=-45,{b,k})
False
(Straight from the text book example)

...I keep getting false, I've tried it with other equations and get the same thing. It's fine when I'm solving a function but when it comes to this remainder theorem I keep getting false. 
Could anyone help me out? Maybe I'm doing it wrong...
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IndefatigableLover

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Re: TI-89 Titanium question
« Reply #1 on: January 20, 2014, 05:06:54 pm »
+1
Quote from: noah the lettuce on January 20, 2014, 05:00:55 pm
Not sure if a setting on my calculator or if I'm entering it wrong but every time I try to solve a certain line on my calculator... e.g
Define p(x)=3x^3+kx^2+bx-5
Done
Solve(p(1)=0 and p(-2)=-45,{b,k})
False
(Straight from the text book example)

...I keep getting false, I've tried it with other equations and get the same thing. It's fine when I'm solving a function but when it comes to this remainder theorem I keep getting false. 
Could anyone help me out? Maybe I'm doing it wrong...
I don't have a TI-89 but have you made sure that you have a multiplication sign in between the 'k' and 'x' plus the 'b' and 'x'? If you haven't then that might be your answer (since the calculator is treating it as one pronumeral rather than two).
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b^3

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Re: TI-89 Titanium question
« Reply #2 on: January 20, 2014, 05:10:40 pm »
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Did you put a times between 'k' and 'x^2' as well as between 'b' and 'x'? If not then it'll come out false as it'll treat 'bx' as a single variable rather than as the product of two variables.

EDIT: Beaten, also don't have a TI-89.
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noah the lettuce

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Re: TI-89 Titanium question
« Reply #3 on: January 20, 2014, 05:16:02 pm »
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Quote from: IndefatigableLover on January 20, 2014, 05:06:54 pm
I don't have a TI-89 but have you made sure that you have a multiplication sign in between the 'k' and 'x' plus the 'b' and 'x'? If you haven't then that might be your answer (since the calculator is treating it as one pronumeral rather than two).
Quote from: b^3 on January 20, 2014, 05:10:40 pm
Did you put a times between 'k' and 'x^2' as well as between 'b' and 'x'? If not then it'll come out false as it'll treat 'bx' as a single variable rather than as the product of two variables.

EDIT: Beaten, also don't have a TI-89.

Well there's my problem, didn't know I had to put the multiplication signs for those! Thanks heaps, I would have been sitting around for another year trying to figure it out
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