Andrew M. answered • 12/28/16
Tutor
New to Wyzant
Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors
Order of Operations:
PEMDAS: parenthesis, exponents, Multiplication/Division (left to right), Addition/Subtraction (left to right)
8-(-3)*5+(-4)
8+3*5-4
8+15-4
23-4
19
Andrew M.
In actuality the first step is:
-(-3) which is a multiplication of -3 by -1
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12/28/16
Kenneth S.
I disagree. Scanning from L to R, you get 8, and then you find -, so what you know at that point is SOMETHING WILL BE SUBTRACTED FROM 8.
Now you search for that something ('subtrahend'), and you find a shrink-wrapped negative three (parentheses are there to prevent two successive operators). When you realize that (-3) is a CANDIDATE for subtrahend, you must postpone its use BECAUSE said (-3) must be involved in a multiplication--that defers the subtraction until the subtrahend is realized, i.e. the product "NEGATIVE 15" has to be computed, and that's the desired subtrahend.
NOW you are at this stage: 8-[-15] + (-4) and the rest is smooth sailing.
R.S.V.P.
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12/28/16
Andrew M.
You are welcome to disagree. In this case it truly doesn't make a difference. That doesn't change the fact that -(-3) is indeed multiplication.
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12/28/16
Andrew M.
5-2(-7)*3
5+14*3
5+42
47
5-2(-7)*3
5-(-14)*3
5-(-42)
5+42
47
The argument is facetious.
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12/28/16
Kenneth S.
Not facetious. If you distribute the subtraction symbol into the (-3), then you must gratuitously replace that subtraction symbol by + so that you can ADD the upcoming product, negative 15. My experience with this comes from many years in the computer business including some association with 'automatic formula translation' in connection with programming languages such as Fortran and COBOL. David W's accurate (and subtle) contribution to this discussion is appreciated. The strict interpretation is necessary in order to maintain an internal list (from a programming standpoint) of binary operators, in proper PEMDAS order, and their associated TWO arguments.
Sorry, student, this has become a battle of experts, and the correct answer is still 19--but we had to get this absolutely correct--it's a very technical algorithm.
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12/28/16
Andrew M.
The true point is that we were discussing a simple line problem - not computer programming. Whether I distribute the -(-3) prior to the *5 makes absolutely zero difference here. I agree that your argument has some merit; and, yes, I also appreciate David W's rather more subtle input. Perhaps others should take note of that approach.
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12/28/16
Kenneth S.
12/28/16