Jolon used the slope-intercept form to write the equation of a line with slope 3 that passes through the point (5, –2). His work
is shown below. Step 1: Negative 2 = 3 (5) + b
Step 2: negative 2 = 15 + b
Step 3: Negative 2 + 15 = 15 + 15 + b
Step 4: Negative 13 = b
Step 5: y = 3x – 13
Analyze the steps. In which step did the Jolon make an error?
He switched the x- and y- values in step 1.
He multiplied incorrectly in step 2.
He added 15 to both sides in step 3.
He forgot to add the b-value in step 5.
Answer. Jolon’s mistake was that he added 15 to both sides in step 3.
Explanation: To cancel something out on one side of the equation, we would do the opposite of what it’s sign is. If it’s positive, we subtract. If it’s negative, we add.
In Jolon’s case here, 15 was positive, which means the correct thing to do is to subtract 15 from both sides. He added instead, which was incorrect.
I hope this helps! Please comment if you have any questions.
