Question

When graphing the equation y=-3x+2, a student plotted the y-intercept at 2, then moved down three units and to the left 2 units because the slope is negative, so both rise and run are negative. Find this error and correct it.

Answer 1

The y intercept at 2 is correct. This is the location (0,2)

The slope is -3 or -3/1, meaning that we move down 3 and to the right 1 unit. Doing so has us go from (0,2) to (1,-1). Plot these two points together on the same xy grid and draw a straight line through the two points.

See below.

Answer 2

The error is founded in the slope, specifically in the run.

When seen a negative slope, that only applies to the rise but not the run.

Instead, the student should run 1(not 2) units to the right.

The slope had not mentioned any 2 in the run.

So it would sound like down 3, over 1, starting from 2.