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 + 7.8Step 2: 6.2 + (− 1.6 − 4.4) + 7.8 (commutative property)Step 3: 6.2 − 6 + 7.8Step 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

Formatting first:

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

Step 2 is the associative property (a+b)+c=a+(b+c)

Step 4 is just wrong with -14 instead of 14; seems corrected in step 5.

Answer: He wrote commutative instead of associative in Step 2.