Re: 'and' or 'or'


uryt_567@xxxxxxxxxxx wrote:
> I'm a student teacher with a couple of questions about what my teacher
> said in class:
>
> Given a function with denominator (3x+4)(x-5), the question was to find
> the restrictions on x. The teacher said the restrictions were 5 and
> -4/3. A student raised her hand and said, isn't it 5 *or* -4/3? The
> teacher said, no, it's 'and', because they're both restrictions. I
> found this "explanation" confusing and I think the student did too even
> though she just said "oh, okay" (as students tend to do). I'm no
> expert on logic, but isn't it the case that either one or both of the
> factors, cannot be zero, and so doesn't that mean we should state the
> restrictions as 5 "inclusive or" -4/3?

How can both factors be 0 at the same time? That would mean x is
simultaneously 5 and -4/3. You "inclusive or" makes no sense either.
The teacher was not using "and" in the logical sense but rather
as connection or addition, such as "4 and 2 are 6" as opposed to
the logical "4 AND 2 = 0".

> ---
>
> Another exercise on the handout read: Given f(x) = 3x-2, state the
> restrictions of x when 4 < f(x) < 10. A lot of the students and myself
> were confused by this. I thought she meant what values of x are not
> permitted because the function is undefined at them, which would have
> been none. But when she took the question up, she said she meant, what
> values of x correspond to the function values from 4 to 10. Would you
> consider the way she wrote the question clear?

The difference is the inclusion of the "when" clause. Obviously,
"restriction" means more than simply undefined. Note in the first
problem you are asked what x CANNOT be. In the second, you are
asked what x MUST be. "Cannot" and "must" are both restrictions.

>
> Thanks
> ---

.

Relevant Pages

  • Man, I was a BAD student!
    ... Cocopah Middle School). ... I was a bad student. ... I did okay in Mrs. Chamberlain's classroom throughout all of 4th grade. ... Then, in 5th grade, my teacher was Mrs. Bauer. ...
    (rec.sport.football.college)
  • Re: Lesbian teacher rapist off hook - no jail time
    ... Amy Lilley, 36, a former teacher and softball coach at Lecanto High ... School in Lecanto, Fla., was sentenced yesterday to two years of house ... reading teacher in Florida accused of having sex with a 14-year-old boy ... student in a Houston apartment she rented for the get-togethers. ...
    (soc.men)
  • Lesbian teacher rapist off hook - no jail time
    ... Amy Lilley, 36, a former teacher and softball coach at Lecanto High ... School in Lecanto, Fla., was sentenced yesterday to two years of house ... reading teacher in Florida accused of having sex with a 14-year-old boy ... student in a Houston apartment she rented for the get-togethers. ...
    (soc.men)
  • Re: teaching relational basics to people, questions
    ... CTRS {COURSE, TEACHER, ROOM, STUDENT}, ... in a particular ROOM to a particular STUDENT. ... There is no table R. The only place in the database to record assertions ...
    (comp.databases.theory)
  • Re: On the relationship between teaching and virtuosity
    ... This guy was an excellent technical player and I was ... With respect to the teacher as an ... And is it possible that the virtuoso ... which hopefully ought to motivate the student ...
    (rec.music.classical.guitar)