The problem isn't necessarily that your "rule" is incorrect. It is that
it is too complicated. What does the beginning algebra student do if
there is more than one consecutive subtraction? I think strict left
association is easier to teach and easier to remember.
-- Rick
--- Vinaire <vinaire@yahoo.com> wrote:
> When addition and subtraction are present together they may be
> carried out from left to right.
> 10 – 5 + 8 – 4 = 5 + 8 – 4 =
> 13 – 4 = 9
> 3 + 9 – 4 + 7 = 12 – 4 + 7 =
> 8 + 7 = 15
> When addition and subtraction are present together they may also be
> carried out safely with subtraction first.
> 10 – 5 + 8 – 4 = 5 + 4 =
> 9
> 3 + 9 – 4 + 7 = 3 + 5 + 7 =
> 15
> Mistakes are likely if addition is carried before subtraction.
> 10 + 8 – 6 + 3 = 18 – 9 =
> 9 (incorrect)
> 10 + 8 – 6 + 3 = 10 + 2 + 3 =
> 15 (correct)
>
>
> Can anybody come up with an exception to the above?
>
> Vinaire
>
>
>
>
____________________________________________________________________________________
> Never miss a thing. Make Yahoo your home page.
> http://www.yahoo.com/r/hs
Yahoo! Groups Links
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/Math4u/
<*> Your email settings:
Individual Email | Traditional
<*> To change settings online go to:
http://groups.yahoo.com/group/Math4u/join
(Yahoo! ID required)
<*> To change settings via email:
mailto:Math4u-digest@yahoogroups.com
mailto:Math4u-fullfeatured@yahoogroups.com
<*> To unsubscribe from this group, send an email to:
Math4u-unsubscribe@yahoogroups.com
<*> Your use of Yahoo! Groups is subject to:
No comments:
Post a Comment