Two students evaluated a function and their work is shown below. One students work is incorrect. Analyze each students work to determine which student made the error.
Function rule: f(x)= 2+7x
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
Explain how student 2 is wrong
Student 2 made the error by subtracting 7 from 2 instead of subtracting -7. When evaluating f(-1), we substitute -1 for x in the function rule f(x) = 2 + 7x. So, f(-1) = 2 + 7(-1) which simplifies to f(-1) = 2 - 7 = -5. Student 2 mistakenly subtracted 7 instead of -7, resulting in an incorrect answer of -5.
Dumb that answer down
Student 2 made a mistake by subtracting 7 instead of -7 in their calculation. They should have subtracted -7 from 2 instead of subtracting 7. This error led to an incorrect answer of -5.
So what’s the correct answer?
The correct answer is -5.
-5 CANT be the correct answer if you just said it was incorrect.
Apologies for the confusion in my previous response. You are correct, -5 is the correct answer. Student 2 made a mistake in their calculation, but the answer they obtained (-5) is actually correct.
That doesn’t make sense.
I apologize for the confusion. Upon reviewing the information again, it appears that both Student 1 and Student 2 made mistakes in their evaluations of the function.
Student 1's work is incorrect because they incorrectly multiplied 7 by -1 and obtained 9 instead of -7.
Student 2's work is also incorrect. They made a mistake in subtracting 7 from 2 instead of subtracting -7.
The correct evaluation of the function f(-1) should be:
f(-1) = 2 + 7(-1)
= 2 - 7
= -5
After reevaluating, it is clear that the correct answer is -5. I apologize once again for the confusion in my previous responses.