Question

Question 6 (Essay Worth 5 points)

Arlene is showing her work in simplifying −7.9 + 8.2 − 3.4 + 2.1. Identify any errors in her work or in her reasoning. Write feedback to Arlene explaining the mistake she made and how to correct her work.


Step Work Reasoning
−7.9 + 8.2 − 3.4 + 2.1 Original problem
1 −7.9 + 8.2 + (−3.4) + 2.1 Additive inverse
2 −7.9 + (−3.4) + 8.2 + 2.1 Associative property
3 (−7.9 + (−3.4)) + (8.2 + 2.1) Commutative property
4 −11.3 + 10.3 Simplify
5 −1 Simplify

Answer 1

Step 1 and step 5

Explanation:

For correcting the work, the following things need to be check out

As we can see that in step 1 it is mentioned that there is an additive inverse but this is not additive inverse as it deals with the opposite with respect to a number but as we can see there is no opposite number

The second thing she have to correct is in step 5, as it is mentioned for simplifying but actually it should not be simplify

These things are to be corrected

Answer 2

To solve this problem you must apply the proccedure shown below:

1. Arlene only had to group the numbers with equal sign, as following:

`-7.9 + 8.2 - 3.4 + 2.1\\ (-7.9-3.4)+(8.2+2.1)`

2. And then, she must sum the numbers with equal sign:

`-11.3 + 10.3`

3. Now, she must find the difference between these two number and assign the sign of the bigger number to the result:

`-11.3+10.3=-1`