Question 204·Hard·Nonlinear Functions
The rational function is defined by
where , , and are constants. The partial graph of is shown.
A new function is defined by
Which choice could define function ?
For rational functions of the form , use the graph’s “approach lines” to read (vertical) and (horizontal), then use one labeled point to solve for . Only after the base function is identified should you apply transformations like ; keep the entire expression grouped, substitute it into the denominator, and apply outside operations (like multiplying by 2 and subtracting 3) last.
Hints
Use the dashed lines
The dashed vertical line tells you what value makes the denominator , and the dashed horizontal line tells you the vertical shift.
Plug in the labeled point
After you identify and , use the point to solve for .
Transform carefully
Compute first, then multiply the result by , then subtract .
Desmos Guide
Model with sliders
Enter
and create sliders for , , and .
Match the graph to find and
Adjust so the graph gets very close to the same vertical dashed line as the given graph, and adjust so the graph gets very close to the same horizontal dashed line.
Use the labeled point to determine
After matching and , adjust until the curve passes through the labeled point .
Graph from your
In a new line, enter
Then rewrite that expression by hand into a single fraction plus a constant to match one of the choices.
Step-by-step Explanation
Read and from the dashed lines
From the graph, the curve gets closer and closer to the dashed vertical line at , so the denominator must be and therefore .
The curve also gets closer and closer to the dashed horizontal line at , so the vertical shift is .
So
Use the labeled point to find
The point lies on the graph, so substitute and :
Thus , so and
Substitute into
Replace with :
Apply the outside transformations to get
Now compute :
Simplify
So the correct choice is .