Implied Multiplication and TI Calculators
Date: 05/02/2008 at 09:24:12 From: Rob Subject: Multiplying parenthetical phrases and order of operations I have found that depending on how I type an expression into my TI-85, it comes out with two different answers. If I type 36/6(25-11*2), the answer comes out to be 2. However, if I type 36/6*(25-11*2), the answer comes out to be 18. The difference is whether I put the multiplication symbol between the 6 and the parenthesis or not. I've been under the impression this should make no difference; with or without the symbol, a number up snug against the parenthesis still implies a multiplication symbol. Help?
Date: 05/02/2008 at 13:20:22 From: Doctor Peterson Subject: Re: Multiplying parenthetical phrases and order of operations Hi, Rob. Your two expressions in the calculator are 36 / 6 ( 25 - 11 * 2 ) and 36 / 6 * ( 25 - 11 * 2 ) The problem is that some calculators that allow multiplications to be implied as in the former case treat that as a higher precedence operation (as some algebra texts say), while others treat all multiplications alike (as most texts do, in my experience). You can read a little about that here: Order of Operations http://mathforum.org/library/drmath/view/54341.html That has a bad link to TI's site; a current version can be found by going to their Knowledge Base and searching for "implied multiplication". Here is a quote: Solution 11773: Implied Multiplication Versus Explicit Multiplication on TI Graphing Calculators. Does implied multiplication and explicit multiplication have the same precedence on TI graphing calculators? Implied multiplication has a higher priority than explicit multiplication to allow users to enter expressions, in the same manner as they would be written. For example, the TI-80, TI-81, TI-82, and TI-85 evaluate 1/2X as 1/(2*X), while other products may evaluate the same expression as 1/2*X from left to right. Without this feature, it would be necessary to group 2X in parentheses, something that is typically not done when writing the expression on paper. This order of precedence was changed for the TI-83 family, TI-84 Plus family, TI-89 family, TI-92 Plus, Voyage™ 200 and the TI-Nspire™ Handheld in TI-84 Plus Mode. Implied and explicit multiplication are given the same priority. If you have any further questions, feel free to write back. - Doctor Peterson, The Math Forum http://mathforum.org/dr.math/
Search the Dr. Math Library:
Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.