Question

Matt is showing his work in simplifying (6.2 − 1.6) − 4.4 + 7.8. Identify any error in his work or reasoning.

Step 1: (6.2 − 1.6) − 4.4 + 7.8
Step 2: 6.2 + (− 1.6 − 4.4) + 7.8 (commutative property)
Step 3: 6.2 − 6 + 7.8
Step 4: −14 − 6 = 8 (commutative property)
Step 5: 14 − 6 = 8

He wrote commutative instead of distributive in Step 4.

He wrote commutative instead of distributive in Step 2.

He wrote commutative instead of associative in Step 4.

He wrote commutative instead of associative in Step 2.

Answer 1

@JoannaBlackwelder

Answer 2

Do you know what the commutative property is?

Answer 3

@realmadrid7 ?

Answer 4

a + b = b + a

Answer 5

Good! Does step 2 use that property?

Answer 6

yes

Answer 7

It looks like the numbers are in the same order to me.

Answer 8

All that changed were the parentheses, right?

Answer 9

yea

Answer 10

No negatives changed. One subtraction got changed to adding a negative, but that is not the commutative property.

Answer 11

So, what is the property that says you can move the parentheses?

Answer 12

(a+b)+c=a+(b+c)
Which property is this?

Answer 13

distrbutive property right ?

Answer 14

No, that is a(b+c)=ab+ac

Answer 15

?

Answer 16

assosative property

Answer 17

Right :)

Answer 18

mybad lol

Answer 19

haha, no worries

Answer 20

so it would be d right

Answer 21

@realmadrid7

Answer 22

Do you remember if d was right?