9. A. She used y-values where she should have used x-values.

B. She did not keep the order of the points the same in the numerator and the denominator.

C. She mixed up the x- and y-values.

D. She should have added the values, not subtracted them.

B. She did not keep the order of the points the same in the numerator and the denominator.

Step-by-step explanation:

The formula to calculate slope is:

She instead used this formula:

The student made the mistake of not keeping the numerators and denominators in the same order.

2 and 1.

step-by-step explanation:

plug in each answer. 0 doesn't work, 1 does. so does 2. 4 doesn't:

0 = 1 is not true.

2 = 2 is true.

4 = 4 is true.

8 = 16 is not true.

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