(-4)(-3) ÷ 6 - 2[5 - -8 + (6 ÷ 2)] I need help with this problem. Thanks

17

Solve the problem in the parens first -- (6 divided by 2).

(-4)(-3) ÷ 6 - 2[5 - -8 + (6 ÷ 2)]
(-4)(-3) ÷ 6 - 2[5 - -8 + 3]
etc.

(Write down each step one after the other. Do one calculation in each step.)

WG:

You forgot something. Precedence of operators. * & / are at the same level and should be done first the + & - are at the same level and should be done second if no parenthesis.

e.g. for part of your problem:

(-4)(-3) ÷ 6

Is (-4)(-3)/6

You don't have to work with big numbers because 3 is a factor of 6 so..

(-4)(-1)/2 is the same and

(-2)(-1) is the same

So ans is 2 which would also be 12/6 doing it the "harder" way.

Hmmm, my math teachers never told me that. Since I've been out of school for 1,000 years, I bow to your knowledge and skills, KISS.

Well, the way to remember the order of 'priority' should I say is:

BODMAS

Which means that you start first with:
Brackets
Of
Division
Multiplication
Addition
Subtraction

And the answer is not 17.

Lol, yes, but you just didn't say what to do when no more brackets remains, for example, in a similar case when it gets from:

(-4)(-3) ÷ 6 - 2[8 + 10 - 2]
(-4)(-3) ÷ 6 - 32

In this case, you work out the division first, and last the subtraction :)

EDIT: Forgot to specify that it was a side example.

Lol, yes, but you just didn't say what to do when no more brackets remains
The OP was online when I said what I did, and I expected a response, but after fifteen minutes or so, he disappeared after saying nothing. I definitely wanted feedback and wasn't going to hand him the entire solution without his input.

unky:

You missed one "unary minus" e.g. -2^3

unky:

You missed one "unary minus" e.g. -2^3

Oh right! Anyway, this was an example and was not necessarily the next part of the problem :)

Okay. Someone please do about half of this problem, with one calculation per line.

(-4)(-3) ÷ 6 - 2[5 - -8 + (6 ÷ 2)]
(-4)(-3) ÷ 6 - 2[5 - -8 + 3]
Then?

(-4)(-3) ÷ 6 - 2[5 - -8 + 3]

Since you can either add or subtract, go from left to right.

(-4)(-3) ÷ 6 - 2[13 + 3]

Subtract:

(-4)(-3) ÷ 6 - 2[16]

Multiply:

(-4)(-3) ÷ 6 - 32

It's nearly done now...

Huh?

5 - -8 + 3 = 10?

5 + 8 + 3 = 16 by the math I learned.

The authority:

](-4)(-3) 6 - 2[5 - -8 + (6 2)] - Wolfram|Alpha (http://www.wolframalpha.com/input/?i=%28-4%29%28-3%29+%C3%B7+6+-+2[5+-+-8+%2B+%286+%C3%B7+2%29)

Well, the math I learned used the BODMAS order, and addition of the -ve 8 with the +ve 3 comes first according to the way I was taught... hmm... or is it some programming stuff, which takes as far as possible, the signs from left to right...

Type "=5--8+3" into Excel; You get 13

Type "=--8" into Excel and you get 8

I just checked to confirm. Seems like I had a 'false' thought about the orders...

Ok, I think I'll edit my post above then not to confuse the OP.

And, I jumped to the first link I found...

Order of Operations - BODMAS (http://www.mathsisfun.com/operation-order-bodmas.html)

To my way of thinking,

5 - -8 + 3 = 0

or, is 5 + -8 + 3 = 0?

5 - -8 + 3 is an EXPRESSION, not an equation. 10=3x is an EQUATION.

I can't believe that your hung up on 5 -(-3)

Remember when 5-3 is the same as 5+(-3). What happened? We inverted the operator and inverted the sign of the operand. We do the same for 5 - (-3) so you get 5 + (+3) or 5 + 3.

Basic principles.

People forget about unary minus which is first in the order of precidence. So 5 * -3 means unary minus is evaulated first.

Unary expressions are a part of high school algebra? I had three years of algebra in high school and college, and never heard that term until today.

Plus and minus signs - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Plus_and_minus_signs)

I never learned the term Unary until I took some computer classes and had to write algebraic to RPN interpreters. RPN = Reverse polish Notation which was the language that early HP calculators used like the HP25.

(5 + 3 ) / 2 would translate into
5 push
3 push
Add
Push 2
Divide
Pop Result

Push and pop are stack operations. The HP25 had a 4 level (First In, Last out) stack, I think. I still use an old LED National Semiconductor calculator that uses RPN which is probably 20-25 years old. Divide would divide the last two items on the stack. The Last item on was the display.

The fun part was that no one would steal your calculator because they could not use it. There was no equal sign. "Can I borrow your calculator?". Sure. There's no equals. I know. Here, Have it back.

There is no "push" key on the calculator. It's replaced by "Enter". There is no parenthesis either, so, I guess you have to know the order of operations.

5 - -3 would be
5 push
3 push
Change sign
Minus

But we're not in computer class. We're doing high school algebra here.

(-4)(-3) ÷ 6 - 2[5 - -8 + (6 ÷ 2)]
(-4)(-3) ÷ 6 - 2[5 - -8 + (3)]

[5 - -8 + (3)] means [five minus negative eight plus three]

Right?

Right.

We are not in high school here. We are in Elementary school. 5 - - 8 can be don on a NUMBER LINE.

Draw number line.
Put pen on -5
With the minus operator go negative
With the unary - operator reverse direction again
So, you moved 8 units in the positive direction from -5.

This is Elementary School stuff.

No, not the unary verbiage. Skip that part.

[5 - -8 + (3)] means [five minus negative eight plus three]

Right? Or wrong?

I said right.

I said right.
Thanks!

I've never heard the word unary either, and no, this isn't a computer class.

It's also not elementary school for someone who went to school 40 years ago! Not all elementary schools even today get into this type of thing, let alone that many years ago. Stop making it sound like "baby stuff" that everyone "should" know.

WG, there was nothing wrong with the way you started this. I don't even know what all the jibberish that followed it was about. You can do the division you did first with no problem.

From there you have several choices. I would have solved the brackets on the right first like Unky did.

5 - - 8 + 3 does indeed equal 5 minus negative 8, but you're coming out with the wrong answer to that. Minus does mean go left on the number line (subtract), but you're minus'ing a negative 8, which puts it back the other direction, to the right. It's like saying the - on the 8 means "go the opposite direction as what you would have otherwise." "Minus a negative" is actually adding. So it's 5 + 8 + 3 = 16.

I was in elementary school too 40 years ago and I swear we had this stuff.

I was in elementary school too 40 years ago and I swear we had this stuff.
I TAUGHT elementary school that many years ago and didn't teach it. I asked my husband who went to "mid- to upper class" Chicago suburban schools, and he had never heard of it either. He builds his own computers and is retired from Western Electric/Lucent as a 5ESS installer and never heard of it there either.

I don't expect anyone to know about Unary minus. Wikipedia mentions how elementary school elude to it.

I've written operating systems as part of a class project and I built a computer when the 8008 was out using just using 7400 series gates as part of a lab with 2 other people. The "computer" couldn't do much but sort 16 numbers, but it was a computer.

In high school I did know about unary minus though because I was involved with computers before the IBM PC. I also took a computer college class and two of my mentors were brothers that were in high school as well and eventually went to MIT. They essentially ran the state's time-sharing network into the high schools. I hacked the system and eventually worked on their side preventing breaches.

Generally, you don't learn about interpreters and RPN until you start taking courses in programming or writing compilers and interpreters. I've written in many machine languages for different processors.

I don't expect it to be taught as Unary minus, but I do know I could add, subtract, multiply and divide by high school.

I don't expect anyone to know about Unary minus. Wikipedia mentions how elementary school elude to it. I don't expect it to be taught as Unary minus, but I do know I could add, subtract, multiply and divide by high school.
Elementary schools allude to it, but don't call it that. And yes, we all could add, subtract, multiply, and divide by high school. At least, most of us could. Those negative numbers can be real tricky. I'm not so sure about how well students today can do basic arithmetic, much less algebra, from what I've seen of teen library volunteers.

And thank you, KISS, for telling me about something (and leading me to research it) that I had never heard of before. I always like to learn new stuff.

Your quite welcome.

Did you know Google does some math: e.g. Google (http://www.google.com/#hl=en&q=5--3&aq=f&aqi=h1&aql=&oq=&gs_rfai=&pbx=1&fp=fb69700481925f55)

Google is my middle name, but I didn't know about that Google function. I bookmarked the Search page for future reference. I owe you another thank you.

I'm not so sure about how well students today can do basic arithmetic, much less algebra, from what I've seen of teen library volunteers.

Hmm, yeah, well don't forget I work with college students... and a few weeks ago I ran across someone who didn't know what half of 6 was. So there you go. :rolleyes: