Question

PLEASE HELP ME WITH THIS PLEASEArlene 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

@Nnesha

Answer 2

@thefluffmuncher

Answer 3

@Will.H

Answer 4

Okay, so first off, is the math she did corect? Only look at the numbers, not the reasoning

Answer 5

Original is 5.2

Answer 6

Is that what you got as the answer?

Answer 7

For the Original problem yes

Answer 8

Step 3 Commutative is Right because communitive does not change

Answer 9

I'm fairly sure The Additive inverse is the problem

Answer 10

Are you there?

Answer 11

Okay, so lets work through this.
Here is the original equation: \[-7.9+8.2-3.4+2.1=?\]
Here is how I like to do these. I like to just work from left to right because to me it is simplier. First lets combine the first two terms. What you should've gotten from adding the first two terms is 0.3 . Now lets plug that into the equation. \[0.3-3.4+2.1=?\]
Now lets combine the first two terms of this. What you should get is -3.1 . Now lets plug that into the equation. \[-3.1+2.1=?\]
Now lets add the last two terms. For the answer to this, you should've gotten -1

Answer 12

I don't see what was wrong with it though?

Answer 13

well we have to go through it to see what is wrong because you have to give feedback. feedback will include the bad things and the good things this person did when solving the problem

Answer 14

Alright

Answer 15

with the long response above we have covered her work and steps. All that is left to check is the reasoning

Answer 16

can you define the reasonings she gave for each step. ex. What is the associative propery

Answer 17

I don't know associative but ik the others

Answer 18

The associative property states that you can add or multiply regardless of how the numbers are grouped. By 'grouped' we mean 'how you use parenthesis'. In other words, if you are adding or multiplying it does not matter where you put the parenthesis.

Answer 19

okay, so which one do you think doesn't fit with what she has done?

Answer 20

I don't know why but I have a suspicion its the additive inverse

Answer 21

can you give the definition of the Additive Inverse property?

Answer 22

Its a number

Answer 23

I gtg, but I'll be back on in about an hour.

Answer 24

its a number plus its opposite equals zero

Answer 25

okay, so does what this person did represent that property?