SOLUTION: how to evaluate 7 to the power of 2 - 3 to the power of 2 + 4

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Question 1208477: how to evaluate 7 to the power of 2 - 3 to the power of 2 + 4

Found 3 solutions by ikleyn, greenestamps, Edwin McCravy:
Answer by ikleyn(52778) About Me  (Show Source):
You can put this solution on YOUR website!
.
how to evaluate 7 to the power of 2 - 3 to the power of 2 + 4
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As it is expressed in wording form, I do understand it this way:


    (1)  7 to the power of (2-3) is 7 to the power of (-1),  or  7%5E%28-1%29 = 1%2F7.


    (2)   1%2F7  to the power  of (2+4)  is  1%2F7  to the power  6,  or  

                     %281%2F7%29%5E6 = 1%2F7%5E6 = 1%2F%287%2A7%2A7%2A7%2A7%2A7%29 = 1%2F117649.    ANSWER

Solved, answered and explained.

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The overall impression is as if someone slept for 400 years and then suddenly woke up and started ventriloquizing.


In reality, in contemporary Math nobody and never uses such wording description as it is in this post -
- it never works properly and it is commonly considered as a hopelessly outdated bad old style.

Instead, for clarity, a standard formal mathematical writing was invented, developed
and is used to avoid ambiguity and misunderstanding.

Formal mathematical writing is a standard style of thought transference in Math everywhere - in Math articles,
in Math magazines, in Math monographs, in Math textbooks, in Math web-sites and even in separate Math problems.

This style of wording in Math, as presented in the post, was used thousands and hundreds years ago, but it is just, probably,
300 - 400 years or about it as this wording style is not used. Formal mathematical language was developed and is in use, instead.


Perhaps, you have heard or know the old fairy tales by the Brothers Grimm, that relate to life of 400 - 500 and more years ago,
where the evil old witch cooked porridge in a pot. This verbal style in your post refers precisely to that time.


Whether you could turn the wheel of history 400 years back, then your wording would be appropriate.


Or, it may be better to say that even then such wording would not be appropriate, since it is ambiguous.


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        The oral style of transference thoughts is not used
        in printed documents since the invention of printing.

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The bottom line is :   do not post problems presented in this style to this forum in order for do not scare the readers.

We just live in the  XXI  century.   The year now is   2024.



------- Specially for Edwin with his objections, I repeat -------

        The oral style of transference thoughts is not used
        in printed documents since the invention of printing.

*********************************************************



Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


The wording is indeed bad, as tutor @ikleyn says in her response.

I read the expression differently than she does, as

7%5E2-3%5E2%2B4

This evaluates, very simply, to

49-9%2B4=44


Answer by Edwin McCravy(20054) About Me  (Show Source):
You can put this solution on YOUR website!
how to evaluate 7 to the power of 2 - 3 to the power of 2 + 4
I think the student didn't know that the caret " ^ " is used for exponents,
and wrote the words "to the power of" in place of carets.

To the student: A caret " ^ " is used for an exponent because it points
up to where the exponent should be, but the keyboard can't put it up there.

Anyway, I don't see why the "PEMDAS"-rule shouldn't be assumed to be followed
whether a problem is written in English words or mathematical symbols.
It's written the way somebody would vocalize it, as if they were speaking
it to somebody, say, on a cell phone.

So I see nothing wrong with the wording.  It is equivalent to this:

7%5E2-3%5E2%2B4

49-9%2B4

44

Edwin