Question 200·Medium·Nonlinear Functions
The graph shows the quadratic function .
Which choice could be the equation of ?
For a quadratic graph, first identify the -intercepts to write a factored form . Then use one additional visible point (often the -intercept) to solve for the scale factor . Finally, confirm the opening direction matches the sign of .
Hints
Read the intercepts
Look at where the parabola crosses the -axis. Those -values tell you the factors of the quadratic.
Start with factored form
If the -intercepts are and , you can write .
Use the y-intercept to find the scale
Plug in the point where the graph crosses the -axis (where ) to determine the value of .
Desmos Guide
Enter the candidate equations
In Desmos, enter each answer choice as a separate equation (for example, type , then the other three).
Compare intercepts to the graph
For each curve, check whether it crosses the -axis at and and whether it crosses the -axis at .
Select the matching equation
Choose the equation whose graph matches the given parabola in intercepts and in whether it opens upward or downward.
Step-by-step Explanation
Use the x-intercepts
The graph crosses the -axis at and .
So the quadratic can be written as
for some constant .
Use another point to find
The graph crosses the -axis at .
Substitute and into :
So .
Write the equation
With , the equation is .