Question

Two students evaluated functions with a given input and their work is shown below. One student is incorrect. Analyze their work to determine which student’s work is correct and describe the mistakes made.

Function Rule:
f(x)= 2 + 7

Student 1:
f(-1)= 2 + 7 (-1)
f(-1)= 9 (-1)
f(-1)= -9

Student 2:
f(-1)= 2 + 7 (-1)
f(-1)= 2-7
f(-1)= -5

Use the words input, output, order of operations, and function, in your explanation sentence.

Answer 1

The correct evaluation of the function with an input of -1 is given by Student 2. Student 1 made a mistake by incorrectly multiplying 7 with -1 instead of adding it to 2. This mistake violates the order of operations, where multiplication must be performed before addition. Therefore, the correct output for f(-1) is -5.