Given the function f(x) = x2 and k = 3, which of the following represents the graph becoming more narrow?
2 answers:
Functions A and C and D are translations - this means that they are exactly the same shape as f(x), but are displaced on the axes. A translation in the y-direction by k units is represented by f(x) + k, and a translation in the x-direction by k units is represented by f(x - k). This can be summarised in column vector notation:
A translation of the graph y = f(x), by the vector![\left[\begin{array}{ccc}a\\b\end{array}\right]](https://tex.z-dn.net/?f=%20%20%5Cleft%5B%5Cbegin%7Barray%7D%7Bccc%7Da%5C%5Cb%5Cend%7Barray%7D%5Cright%5D%20)
results in the graph defined by y - b = f(x - a). This is done by replacing x with (x - a) and y with (y - b). Finally it is rearranged to make y the subject, as is often the convention: y = f(x - a) + b.
Since the graph needs to change shape, this requires a 'stretch'. A stretch is performed by multiplying x or y by a constant, which here is k.
To stretch in the x-direction by a factor n, replace x with (1/n)x. Similarly to stretch in the y-direction by a factor n, replace y with (1/n)y.
For example to stretch y = f(x) by factor n in the x-direction, it would become y = f((1/n)x).
A simple quadratic graph like y = x^2 behaves slightly differently to most other graphs, in that it can narrowed by a stretch in the x or y direction. This means that a more convenient option is to perform a stretch in the y direction, since the multiplier lies outside the function notation. The stretching factor is 3, so we replace y with (1/3)y:
(1/3)y = f(x)
y = 3f(x)
Since k = 3, this becomes
y = kf(x)
... and hence the correct answer is B
A translation of the graph y = f(x), by the vector
Since the graph needs to change shape, this requires a 'stretch'. A stretch is performed by multiplying x or y by a constant, which here is k.
To stretch in the x-direction by a factor n, replace x with (1/n)x. Similarly to stretch in the y-direction by a factor n, replace y with (1/n)y.
For example to stretch y = f(x) by factor n in the x-direction, it would become y = f((1/n)x).
A simple quadratic graph like y = x^2 behaves slightly differently to most other graphs, in that it can narrowed by a stretch in the x or y direction. This means that a more convenient option is to perform a stretch in the y direction, since the multiplier lies outside the function notation. The stretching factor is 3, so we replace y with (1/3)y:
(1/3)y = f(x)
y = 3f(x)
Since k = 3, this becomes
y = kf(x)
... and hence the correct answer is B
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Answer:
The input value or independent variable is number of questions that you answer correctly on this quiz (variable x)
Step-by-step explanation:
Let
x ----> the number of questions that you answer correctly on this quiz
y ----> the total number of points you score on this quiz
In this problem
The output value or dependent variable is the total number of points you score on this quiz (variable y)
The input value or independent variable is number of questions that you answer correctly on this quiz (variable x)
we have
This linear equation represent a proportional relationship between the variables x and y
where
k=10
K is the constant of proportionality or slope of the linear equation