Question

PLS HELP!!!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.

the way she did it was

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

I started with -7.9+8.2-3.4+2.1=-1.

Answer 2

The errors are in 2 and 3 step.

Explanation:

The first step is correct.

Now, in the second step she rearranged positive terms on right and negative terms on left, that is posible by commuttative property, not associative.

Then, she grouped each pair of terms, that is posible by associative property, not commutative.

4 and 5 step are correct.