Question 52·Easy·Nonlinear Functions
Which table gives three values of and their corresponding values of for the function ?
For function-value questions like this, ignore the tables at first and go straight to the formula: plug each given x-value into the function carefully using the correct order of operations (square, then multiply, then add/subtract). Once you have the exact outputs (like , , ), quickly scan the answer choices and eliminate any table that has even one mismatched value; there is no need to compute anything for the wrong tables themselves.
Hints
Use the definition of the function
You are given . To find , , and , plug each of these x-values into the expression and simplify.
Start with x = 0
What do you get when you substitute into ? Remember that , and then follow the order of operations.
Then try x = 1 and x = 2
After you find , repeat the same steps for and . Once you have all three values, compare them to the rows in each table and see which one matches exactly.
Desmos Guide
Enter the function into Desmos
In Desmos, type p(x)=2x^2-3 on a new line so that Desmos defines the function and shows its graph.
Create a table of values
Click the "+" icon and choose "Table", then in the x-column enter 0, 1, and 2. In the y-column, type p(x) so Desmos automatically fills in the corresponding values for each x.
Compare with the answer choices
Look at the values in your Desmos table for and then choose the answer option whose row matches all three of those values exactly.
Step-by-step Explanation
Understand what the function notation means
The function is defined by .
This means: for any input , you first square , then multiply by 2, and finally subtract 3. You need to do this for , , and .
Evaluate the function at x = 0
Compute by substituting into the formula:
So, any correct table must have in the row under .
Evaluate the function at x = 1 and x = 2
Now substitute :
Then substitute :
So the three ordered pairs should be , , and for .
Match your results to the correct table
Look at each answer choice and check the row for .
The only table whose values are when , when , and when is:
| 0 | 1 | 2 | |
|---|---|---|---|
| -3 | -1 | 5 |
So this table (choice D) is the correct answer.