# ti 89 help

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• Nov 18th 2009, 10:33 AM
saltflat
ti 89 help
I cannot figure out how to input a cube root into this calculator. I can do it with my ti 83 but it converts it into decimals. I need the cube root in front of the square root sign.
• Nov 18th 2009, 10:48 AM
masters
Quote:

Originally Posted by saltflat
I cannot figure out how to input a cube root into this calculator. I can do it with my ti 83 but it converts it into decimals. I need the cube root in front of the square root sign.

Hi saltflat,

If you don't have a cube root function like the TI-83/84 has, then just raise the base to the one-third power.

Example: Cube root of 27 = $\displaystyle 27^{\frac{1}{3}}$
• Nov 18th 2009, 11:07 AM
bigwave
the input on the home display would
be
8^(1/3)

will return 2
• Nov 18th 2009, 04:08 PM
saltflat
okay an example of what i need is i have the problem with a cube root of 16 which my book is telling me the answer should be 2 the square root check with my cube root then another two under this. what am i doing wrong.
• Nov 18th 2009, 04:54 PM
mr fantastic
Quote:

Originally Posted by saltflat
okay an example of what i need is i have the problem with a cube root of 16 which my book is telling me the answer should be 2 the square root check with my cube root then another two under this. what am i doing wrong.

Your problem is that you don't understand the basic algebra of surds.

$\displaystyle \sqrt[3]{16} = \sqrt[3]{8 \times 2} = \sqrt[3]{8} \times \sqrt[3]{2} = 2 \sqrt[3]{2}$.