Homework Help: Algebra

Posted by CC on Sunday, December 12, 2010 at 10:32am.

An operation is commutative if you can change the order of the numbers involved without changing the result. Addition and multiplication are both commutative. Subtraction is not commutative: 2 - 1 is not equal to 1 - 2. So my question is what’s the difference between 2 - 1 and 1 - 2?

Algebra - Jen, Sunday, December 12, 2010 at 11:08am
2-1=1 and 1-2=-1
Algebra - drwls, Sunday, December 12, 2010 at 11:09am
2-1 = 1 and 1-2 = -1.
So the difference is 2.

If you asking why it is that way, it just IS. It can be deduced logically from how subtraction is defined.
Algebra - olav, Sunday, December 12, 2010 at 11:48am
There is no difference between 1-2 and 2-1 if you disregard the + or - in the final answer.

Sometimes when I do calculations on the calculator and I forget which number is the larger, I will end up with a negative answer. I just remember that the answer should be positive. Look at the equation and you can see if the answer should be + or -.

Answer this Question

Related Questions

Algebra - 55. Find the range of y = 2x + 1. a. all real numbers b. all positive ...
Algebra - 55. Find the range of y = 2x + 1. a. all real numbers b. all positive ...
Algebra - 55. Find the range of y = 2x + 1. a. all real numbers b. all positive ...
Algebra - 55. Find the range of y = 2x + 1. a. all real numbers b. all positive ...
MATH - What is commutative property of addition? The commutative property of ...
MATH - What are the 3 property names of addition? 1. The Zero Property of ...
Pre-Algebra: HELP PLEASE - I'm really bad at these, can someone help me ...
Math-properties - c(a*b) = (c*b)a Is this commutative, associative, or both? It ...
Math - 1. 3+2+1=1+2+3 2. 3(1+4)=(3x1)+(3X4) 3. 9(5+6)=45+54 4. 9+(4+3)=(4+3)+9 5...
physics - Does the multiplication of a scalar and a vector display the ...

For Further Reading

First Name:
School Subject:
Answer: