All SAT II Math I Resources
Example Questions
Example Question #12 : Transformation
What would become if it was reflected over the y-axis to become ?
When a function is reflected over the y-axis, .
becomes
which is simplifed as
.
Example Question #3 : Transformation
Let f(x) = x3 – 2x2 + x +4. If g(x) is obtained by reflecting f(x) across the y-axis, then which of the following is equal to g(x)?
x3 + 2x2 + x + 4
–x3 + 2x2 – x + 4
–x3 – 2x2 – x + 4
–x3 – 2x2 – x – 4
x3 – 2x2 – x + 4
–x3 – 2x2 – x + 4
In order to reflect a function across the y-axis, all of the x-coordinates of every point on that function must be multiplied by negative one. However, the y-values of each point on the function will not change. Thus, we can represent the reflection of f(x) across the y-axis as f(-x). The figure below shows a generic function (not f(x) given in the problem) that has been reflected across the y-axis, in order to offer a better visual understanding.
Therefore, g(x) = f(–x).
f(x) = x3 – 2x2 + x – 4
g(x) = f(–x) = (–x)3 – 2(–x)2 + (–x) + 4
g(x) = (–1)3x3 –2(–1)2x2 – x + 4
g(x) = –x3 –2x2 –x + 4.
The answer is –x3 –2x2 –x + 4.
Example Question #21 : Transformations
What is the period of the function?
1
π
4π
3π
2π
4π
The period is the time it takes for the graph to complete one cycle.
In this particular case we have a sine curve that starts at 0 and completes one cycle when it reaches .
Therefore, the period is
Example Question #22 : How To Find Transformation For An Analytic Geometry Equation
Assume we have a triangle, , with the following vertices:
, , and
If were reflected across the line , what would be the coordinates of the new vertices?
When we reflect a point across the line, , we swap the x- and y-coordinates; therefore, in each point, we will switch the x and y-coordinates:
becomes ,
becomes , and
becomes .
The correct answer is the following:
The other answer choices are incorrect because we only use the negatives of the coordinate points if we are flipping across either the x- or y-axis.
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