How do you do a cube root on a TI-89?

Discussion in 'Archived Threads 2001-2004' started by Scott Burke, Jan 9, 2002.

  1. Scott Burke

    Scott Burke Second Unit

    Joined:
    Nov 27, 2000
    Messages:
    479
    Likes Received:
    31
    Trophy Points:
    0
    Location:
    United States
    Real Name:
    Scott B.
    I have looked through the instruction manual, but I cannot figure out how to do it. Anyone know?
     
  2. Daryl Furkalo

    Daryl Furkalo Second Unit

    Joined:
    Dec 8, 2000
    Messages:
    372
    Likes Received:
    0
    Trophy Points:
    0
    I have a TI-85, so how about ^1/3? Should be right.
     
  3. BrianW

    BrianW Cinematographer

    Joined:
    Jan 30, 1999
    Messages:
    2,563
    Likes Received:
    38
    Trophy Points:
    0
    Real Name:
    Brian
    Alternatively, you could follow these steps:
    Enter the number you want to find the cube root of.
    Press the [ INV ] key.
    Press the [ x^y ] key.
    Press the [ 3 ] key (or enter any root value you want).
    Press the [ = ] key.
    Your answer will be in the display.
    Doing Inverse-Power is the same thing as finding a root.
     
  4. Joe D

    Joe D Supporting Actor

    Joined:
    May 21, 1999
    Messages:
    838
    Likes Received:
    1
    Trophy Points:
    0
    The easiest way to do this is to take x to the (1/3) power. Instead of a cube root.
     
  5. BrianW

    BrianW Cinematographer

    Joined:
    Jan 30, 1999
    Messages:
    2,563
    Likes Received:
    38
    Trophy Points:
    0
    Real Name:
    Brian
     
  6. Artur Meinild

    Artur Meinild Screenwriter

    Joined:
    Aug 10, 2000
    Messages:
    1,294
    Likes Received:
    0
    Trophy Points:
    0
    Brian, in some funny way you contradict yourself. What you suggested in the previous post *was* to take x to the 1/3 power... [​IMG]
    It's just a matter of the easiest combination of keystrokes - on a HP calc, the easiest way would be [3] [INV] [X^Y]...
     
  7. BrianW

    BrianW Cinematographer

    Joined:
    Jan 30, 1999
    Messages:
    2,563
    Likes Received:
    38
    Trophy Points:
    0
    Real Name:
    Brian
     
  8. Bill Catherall

    Bill Catherall Screenwriter

    Joined:
    Aug 1, 1997
    Messages:
    1,560
    Likes Received:
    0
    Trophy Points:
    0
    One more reason to own an HP 48G. [​IMG] We get a button (actually a shifted button) that lets you take any root you want without having to inverse it (but it takes the same number of key strokes either way...minimum of 5). It's just that the button is right there waiting to be used.
    (Hey...we're all sick of the Mac vs. PC debate. Time to start an HP vs. TI war. [​IMG] )
     
  9. Denward

    Denward Supporting Actor

    Joined:
    Feb 26, 2001
    Messages:
    552
    Likes Received:
    0
    Trophy Points:
    0
    How about take the log of the number, dividing it by 3, and then hitting 10^x.[​IMG]
    I believe that the easiest method is not the one with the least keystrokes, but the one that's most intuitive and repeatable for you.
    BTW, I'm an HP man but I use their business calculators. I used to use the 12C but now I really like my 17BII.
     
  10. Scott Burke

    Scott Burke Second Unit

    Joined:
    Nov 27, 2000
    Messages:
    479
    Likes Received:
    31
    Trophy Points:
    0
    Location:
    United States
    Real Name:
    Scott B.
    Thanks for the replies guys! I never thought of doing it that way. I just assumed that because my trusty TI 85 had a button for it so would the 89. However, I realize that is not the case. Thanks!
     

Share This Page