Question

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

@DanJS

Answer 2

@iambatman

Answer 3

@Ahsome ? anything

Answer 4

There is no errors

Answer 5

are*

Answer 6

Keep doing each step manually, and see where it slips up:
\[−7.9 + 8.2 − 3.4 + 2.1=-1\]
\[−7.9 + 8.2 + (−3.4) + 2.1=-1\]
\[−7.9 + (−3.4) + 8.2 + 2.1=-1\]
\[(−7.9 + (−3.4)) + (8.2 + 2.1)=-1\]
\[−11.3 + 10.3 =-1\]