Question

Your friend asks you to check their work. You see the expression 3(15−9)2 + 2 ⋅5

simplified in the following way:

Original Problem: 3(15−9)2 + 2 ⋅ 5
Step 1: 3(6)2 + 2 ⋅5
Step 2: 3(36)+ 2 ⋅ 5
Step 3: 108 + 2 ⋅ 5
Step 4: 110 ⋅ 5
Step 5: 550
Part A: Explain, using complete sentences, in which step and what specifically your friend's error was.



Part B: Correctly simplify this expression using a similar format - showing work for each step like was done above. Full credit will only be given if work shows Step 1, Step 2, Step 3, etc. as seen above.

Answer 1

118

Explanation:

Part A:

My friend's error is in Step 4, where they multiply 110 by 5 instead of adding 110 and 2 • 5.

Part B:

Step 1: 3(15-9)² + 2 • 5

Step 2: 3(6)2 + 2 • 5

Step 3: 3(36) + 2 • 5

Step 4: 108 + 2(5)

Step 5: 108 + 10

Step 6: 118

Therefore, the correct simplified expression is 118.