Pearson Algebra 2 Common Core, 2011
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Pearson Algebra 2 Common Core, 2011 View details
End-of-Course Assessment

Exercise 55 Page 969

Practice makes perfect
a

We will graph the parent reciprocal function f(x)= 1x. To do so, we will first make a table of values to see the positive and negative values of x.

f(x)=1/x
x 1/x (x,y)
- 4 1/- 4 ( -4, -0.25)
- 1 1/- 1 ( -1, -1)
-0.25 1/- 0.25 ( -0.25, - 4)
0 1/0 Undefined
0.25 1/0.25 ( 0.25, 4)
1 1/1 ( 1, 1)
4 1/4 ( 4, 0.25)

Notice that f(x)= 1x is defined for all real numbers except x=0. Therefore, there is no y-intercept. Moreover, since the numerator is never 0, there is no x-intercept. Knowing this, let's connect the points with a smooth curve.


b

We will examine the graph of g(x)= 4x+2 by comparing the graph of f(x)= 1x. To do so, let's remember the general form of the reciprocal function family.

y=a/x- h+ kIn this form, the value of a refers to stretches, shrinks, or reflections of the parent function f(x)= 1x. Moreover, the value of h represents the horizontal translation and k represents the vertical translation. With this in mind, let's examine g(x). g(x) = & 4/x+2 ⇕ g(x) = & 4/x-( -2)+ 0 As we can see, g(x) is a stretch of the graph of f(x) by a factor of 4 and it is followed by a translation 2 units to the left. Let's see them on the same coordinate plane.

graph of f and g

c

We are asked to find the horizontal asymptote of the graph of g(x). Let's remember that in the general form of the reciprocal function, y= ax- h+ k, the line y= k represents the horizontal asymptote.

g(x) = & 4/x-( -2)+ 0 Therefore, y= 0 is the horizontal asymptote of g(x).
d

This time we will identify the vertical asymptote. One more time, we will recall that in the general form of the reciprocal function y= ax- h+ k, the line x= h represents the vertical asymptote.

g(x) = & 4/x-( -2)+ 0 Therefore, x= -2 is the vertical asymptote of g(x). Notice that the function is undefined at x= -2 because it makes the denominator 0. x-( -2)=0 ⇔ x= -2 This means that -2 is not included in the domain of the function. We can conclude that the domain of a rational function does not include the vertical asymptotes.