Question about Texas Instruments TI-89 Calculator

# Solve() gives me wrong answer. -20^2=12^2+2X(-5-3). The answer is -16, But my TI-89 is giving me 34 during the solve funtion. my TI-83 is also giving me -20^2=-400 not 400.

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### Stevan Milanovic

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For the first problem you have to type: solve(-20^2=12^2+(2*X*(-5-3)),x)
Also, make sure you use the (-) key on the position number 5, just to the right of the decimal point and not the - key and on the number 3 you have type regulary subtraction - key

Posted on Nov 06, 2011

• 1 more comment
• Stevan Milanovic Nov 06, 2011

For the first problem you have to type: solve((-20)^2=12^2+(2*X*(-5-3)),x)
Also, make sure you use the (-) key on the position number 5, just to the right of the decimal point and not the - key and on the number 3 you have type regulary subtraction - key

• Stevan Milanovic Nov 06, 2011

For the first problem you have to type: solve((-20)^2=12^2+(2*X*(-5-3)),x)
Also, make sure you use the (-) key on the position number 5, just to the right of the decimal point and not the - key and on the number 3 you have type regulary subtraction - key

• Stevan Milanovic Nov 06, 2011

For the first problem you have to type: solve((-20)^2=12^2+(2*X*(-5-3)),x)
Also, make sure you use the (-) key on the position number 5, just to the right of the decimal point and not the - key and on the number 3 you have type regulary subtraction - key

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### kakima

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Enter the first term as (-20^2), not as -20^2. Without the parentheses the calculator interprets it as
-(20^2), which is not what you want.

Also, make sure you use the (-) key just to the right of the decimal point and not the - key.

Posted on Aug 31, 2011

• Stevan Milanovic Nov 06, 2011

For the first problem you have to type: solve((-20)^2=12^2+(2*X*(-5-3)),x)
Also, make sure you use the (-) key on the position number 5, just to the right of the decimal point and not the - key and on the number 3 you have type regulary subtraction - key

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Type solve(log(x^5,16)-log(125,64)+log(x^(1/2),4),x,0.5
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Or, you can use equation solver with eqn=0(MATH, then B option)
See captured images below

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### TI89 is giving wrong answer for the integral of sec(x). Please help. It gives the answer as: ln[ |cos(x) / (sin(x)-1)| ] when it should be ln[ |(sin(x)-1) / cos(x)| ]. Why is it giving the wrong...

Hi danagasta,

If my last instructions did not work then you need to reset your RAM. You are missing the negative sign and, I have no idea where you got the absolute value inside the brackets.
Yes, the absolute value are used in books and, on integral tables but, I can asure you that the Ti 89 should not have produce them in this answer.

I'll stand behind that In( -cos(x) / (sin(x)-1)) is the correct answer. You can go ahead and simplify after the calculation to get the answer you want but, that is the good answer that Ti 89 is going to give you for the integral of sec(x).

Errors that do not match the suspected, I am pretty sure that Texas Instruments would have you clear the RAM. I do not like resetting the RAM but, I could not find the cause to why you got the answer you did. And so far no other expert has produced a solution to convince me otherwise.

I was not able to come up with any of the 3 answers MiB8888 did on my Ti 89. I am not saying that they are not good answers, they are book and integral tables answers. You are not going to get them on the Ti 89.

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You're both right, in a way. (-64)^3 is -262144. The square root of that is +/- 512i. Take your choice as to the sign.

For what it's worth, the TI-84, TI-86, TI-89, and the HP 50g all go with the negative value.

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### I received this solution, but at the end the calculator asked me about some invalid certificate. Now the ti 89 is stuck at the boot screen because if I retry, it goes thru the whole process again and asks...

Hello,
The answer I gave you was taken verbatim from the TI FAQ and knowledge base. I copied and pasted the part relevant to you calculator.
In any case, I sent an e-mail message to [email protected], giving the link to your original question and my answer to it. I took the liberty to copy/paste your present message. I also asked about that invalid certificate.
All we can do know is wait for their reply.

k24674.

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