Question

Amber simplified the expression (a4+7a−16)−(12a3−5a+3) below. Amber made her first error at what step

.Problem: (a4+7a−16)−(12a3−5a+3)

Step 1: a4+7a−16−12a3+5a−3

Step 2: a4−12a3+7a+5a−16−3

Step 3: −11a+7a+5a−16−3

Step 4: −11a+12a−16−3

Step 5: −11a+12a−19

Answer 1

Step 3.

Explanation:

Step 3

She wrote that a4 - 12a3 = -11a.

a4 and 12a3 are unlike terms so they cannot be added.