[Foxhouse]

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

[revolllabyellov]

17

[Wondergirl]

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.)

[KISS]

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.

[Wondergirl]

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.

[Unknown008]

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.

[Unknown008]

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.

[Wondergirl]

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.

[KISS]

unky:

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

[Unknown008]

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 :)

[Wondergirl]

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?

[Unknown008]

(-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...

[KISS]

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

[Unknown008]

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...

[KISS]

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

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

[Unknown008]

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

[Wondergirl]

To my way of thinking,

5 - -8 + 3 = 0

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

[KISS]

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.

[Wondergirl]

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.

[KISS]

Plus and minus signs - Wikipedia, the free encyclopedia

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