Question

23. YOU BE THE TEACHER Your friend finds

the difference. Is your friend correct?
Explain your reasoning.
IN
ODIN
3 9
+
2 2
12
= 6
2

Answer 1

Please see below :)

Explanation:

Original problem and friend's solution:

3/2 - 9/2 = |3/2| + |9/2| = 12/2 = 6

First, let's solve the original problem:

3/2 - 9/2 = -6/2 = -3

Now we know that their solution is incorrect.

Here's why:

The absolute value of 3/2 is still 3/2.

The absolute value of -9/2 is 9/2.

If we wanted to use absolute value, we could rewrite the problem this way:

|3/2| - |-9/2| which would still equal 3/2 - 9/2.

It would be incorrect to do this (what the friend did):

|3/2| + |9/2|

They have to understand that -9/2 is negative (and so -9/2, INCLUDING the negative sign, would go into the absolute value bars if we were to use them) and that the subtraction and negative signs mean the same thing.

Hope this helps!

Let me know if I'm incorrect :)