Question

Ben is showing his work in simplifying (3.9 − 9.4) − 0.6 + 6.1. Identify any error in his work or reasoning. (5 points)

Step 1: (3.9 − 9.4) − 0.6 + 6.1
Step 2: 3.9 + (− 9.4 − 0.6) + 6.1 (associative property)
Step 3: 3.9 − 10 + 6.1
Step 4: 3.9 + 6.1 − 10 (identity property)
Step 5: 10 − 10 = 0

Select one:
a. He wrote identity instead of commutative in Step 4.
b. He wrote associative instead of commutative in Step 2.
c. He wrote identity instead of distributive in Step 4.
d. He wrote associative instead of distributive in Step 2.

Answer 1

notice how from step 3 to step 4 they switched the order of -10 and 6.1

this is not the identity property - do you remember which one it is though?

Answer 2

distributive?

Answer 3

hm, not quite, when we switch the order we would call that ~commutative~

that being said what do you think the solution might be?

Answer 4

ohhhh, i see now.

Answer 5

so the answer is a

Answer 6

good