Question

A student solved z + (-0.72) = -2.5 for z using the following steps. Step 1: z + (−0.72) + (−0.72) = −2.5 + (−0.72) Step 2: z = −2.5 + (−0.72) Step 3: z = −3.22 What was the student’s error?

will give 86 points

Answer 1

The student added the same thing instead of the opposite to each side

Add .72 to each side to make -.72 become 0 on the left -2.5 to become -1.78 on the right

Explanation:

z + (-0.72) = -2.5

Add . 72 to each side

z + (-0.72) + .72 = -2.5 +.72

z = -1.78