There is one more type of problem to consider. If an equation is a linear equation, it can be written in slope-intercept form and you can check for the slope and intercept on a graph.

However, if an equation is not linear, you will not be able to check for slope and y-intercept.

This is an example of a quadratic equation: y = -4x² + 3x

This is not linear, but you can use your calculator skills to find the correct answer.

Which graph best represents the graph of y = -4x² + 3x?

Graph the equation on your calculator. Then also check the table for values for the equation.

Look at graph A.

This looks very close to the graph in choice A. It looks like the points (-1, -7), (0, 0) and (1, -1) are on the graph. But don't pick this yet.

Now look at graph B.

This is definitely wrong from the graph. Graph should open downward.

Next look at graph C.

This is definitely wrong from the graph. Graph should open downward.

Last look at graph D.

This looks very close to the graph in choice D. But (1, -1) is not on the graph to the left.

After using your graphing calculator to check and recheck, you can safely say A is correct.

Now try this nonlinear equation: y = x² + 2?

Decide which answer you believe is correct and record in your notes before scrolling down.

Now examine the answers to see the graphing calculator screens and explanations.

Incorrect . The graph does not match. Also, (-2, 6) and (0, 2) are not on the graph given.

Incorrect. The graph does not match. Also, (0, 2) and (1, 3) are not on the graph given.

Incorrect. The graph does not match. Also, (0, 2) and (1, 3) are not on the graph given.

This graph looks correct. The points (0, 2), (1, 3) and (2, 6) are all on the graph. Another correct answer!