Question 177·Hard·Nonlinear Functions
The function is defined by
In the -plane, the graph of is obtained by performing the following transformations on the graph of , in the order given:
- Reflect the graph across the -axis.
- Translate the resulting graph units to the right.
- Translate the resulting graph units down.
What is the value of ?
(Express the answer as an integer)
For transformation questions, convert each geometric move into a precise algebra change: reflection across the -axis means replace with , a shift right by means use , and a shift down by means subtract from the whole function. Apply these changes in the exact order given to build the new function, simplify if helpful, and then substitute the requested -value. Double-check signs (especially from reflections and vertical shifts), since most mistakes come from missing or misapplied negatives.
Hints
Turn each transformation into a change in the formula
Think about how each transformation (reflect, shift right, shift down) changes the equation of the function. Ask: does it change inside the function, or does it add/subtract something outside?
Reflection across the y-axis
For a reflection across the -axis, in the formula for , every becomes . Write a new function that equals .
Horizontal and vertical shifts
A shift right 3 units means replace with in the current function. A shift down 7 units means subtract 7 from the entire function value. Apply these in the given order to build .
Evaluate at x = 2
Once you have an explicit formula for after all transformations, plug in and simplify carefully, watching the negative signs.
Desmos Guide
Enter the original function
In Desmos, type f(x) = (x - 4)(x + 1)(x + 5) to define the original function.
Define the transformed function step by step (or directly)
Either define each step:
g1(x) = f(-x)(reflection across the y-axis)g2(x) = g1(x - 3)(shift right 3)h(x) = g2(x) - 7(shift down 7)
or define it in one line as h(x) = - (x + 1)(x - 4)(x - 8) - 7.
Evaluate h(2)
In a new line, type h(2) or create a table for h(x) and include . Read off the numeric result Desmos displays; that is the value of .
Step-by-step Explanation
Apply the reflection across the y-axis
The original function is
Reflecting across the -axis means we replace with in the formula. So the new function after step 1 is
We can factor out from each factor:
so
Translate the reflected graph 3 units to the right
To shift a graph of right 3 units, we replace with in .
Here , so after shifting right 3 we get
Substitute for :
Simplify each factor:
So
Translate the graph 7 units down
To shift a graph of down 7 units, we subtract 7 from the function value: .
Here , so the final function is
Evaluate h(2) using the final formula
Now substitute into :
Compute each factor:
So
thus
So the value of is .