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The function [tex]\( f(x) = 8x + 1 \)[/tex] is one-to-one.

(a) Find the inverse of [tex]\( f \)[/tex].
(b) State the domain and range of [tex]\( f \)[/tex].
(c) State the domain and range of [tex]\( f^{-1} \)[/tex].
(d) Graph [tex]\( f \)[/tex], [tex]\( f^{-1} \)[/tex], and [tex]\( y = x \)[/tex] on the same set of axes.

(a) What is the inverse of [tex]\( f \)[/tex]?

[tex]\[ f^{-1}(x) = \boxed{\phantom{8x + 1}} \][/tex]

(Simplify your answer. Use integers or fractions for any numbers in the expression.)


Sagot :

Let's methodically work through each part of the given problem.

### (a) Finding the Inverse of [tex]\( f \)[/tex]

The function given is:
[tex]\[ f(x) = 8x + 1 \][/tex]

To find the inverse, [tex]\( f^{-1} \)[/tex], we need to solve for [tex]\( x \)[/tex] in terms of [tex]\( y \)[/tex]:
[tex]\[ y = 8x + 1 \][/tex]

First, isolate [tex]\( x \)[/tex]:
[tex]\[ y - 1 = 8x \][/tex]
[tex]\[ x = \frac{y - 1}{8} \][/tex]

Therefore, the inverse function is:
[tex]\[ f^{-1}(x) = \frac{x - 1}{8} \][/tex]

### (b) Domain and Range of [tex]\( f \)[/tex]

For the function [tex]\( f(x) = 8x + 1 \)[/tex]:

- Since [tex]\( f(x) \)[/tex] is a linear function, it is defined for all real numbers. Thus, the domain of [tex]\( f \)[/tex] is:
[tex]\[ (-\infty, \infty) \][/tex]

- Because [tex]\( 8x + 1 \)[/tex] covers all real numbers as [tex]\( x \)[/tex] varies over all real numbers, the range of [tex]\( f \)[/tex] is also:
[tex]\[ (-\infty, \infty) \][/tex]

### (c) Domain and Range of [tex]\( f^{-1} \)[/tex]

For the inverse function [tex]\( f^{-1}(x) = \frac{x - 1}{8} \)[/tex]:

- The domain of [tex]\( f^{-1} \)[/tex] is the range of [tex]\( f \)[/tex], which is:
[tex]\[ (-\infty, \infty) \][/tex]

- The range of [tex]\( f^{-1} \)[/tex] is the domain of [tex]\( f \)[/tex], which is:
[tex]\[ (-\infty, \infty) \][/tex]

### (d) Graphs of [tex]\( f \)[/tex], [tex]\( f^{-1} \)[/tex], and [tex]\( y = x \)[/tex]

To graph [tex]\( f \)[/tex], [tex]\( f^{-1} \)[/tex], and [tex]\( y = x \)[/tex]:

1. Graph of [tex]\( f(x) = 8x + 1 \)[/tex]:
- It is a straight line with a slope of 8 and a y-intercept of 1.
- Points to plot could include [tex]\( (0, 1) \)[/tex] and [tex]\( (1, 9) \)[/tex].

2. Graph of [tex]\( f^{-1}(x) = \frac{x - 1}{8} \)[/tex]:
- It is a straight line with a slope of [tex]\(\frac{1}{8}\)[/tex] and a y-intercept of [tex]\( \frac{-1}{8} \)[/tex].
- Points to plot could include [tex]\( (0, -\frac{1}{8}) \)[/tex] and [tex]\( (8, 7) \)[/tex].

3. Graph of [tex]\( y = x \)[/tex]:
- This is a straight line with a slope of 1 and passes through the origin.
- Points to plot could include [tex]\( (0, 0) \)[/tex] and [tex]\( (1, 1) \)[/tex].

These three lines should be plotted on the same coordinate axes to visualize how [tex]\( f \)[/tex] and [tex]\( f^{-1} \)[/tex] are reflections over the line [tex]\( y = x \)[/tex].

### Summary of Results

(a) The inverse of [tex]\( f \)[/tex]:
[tex]\[ f^{-1}(x) = \frac{x - 1}{8} \][/tex]

(b) Domain and Range of [tex]\( f \)[/tex]:
Domain of [tex]\( f \)[/tex]: [tex]\( (-\infty, \infty) \)[/tex]
Range of [tex]\( f \)[/tex]: [tex]\( (-\infty, \infty) \)[/tex]

(c) Domain and Range of [tex]\( f^{-1} \)[/tex]:
Domain of [tex]\( f^{-1} \)[/tex]: [tex]\( (-\infty, \infty) \)[/tex]
Range of [tex]\( f^{-1} \)[/tex]: [tex]\( (-\infty, \infty) \)[/tex]

Remember to carefully plot and check the proper scales when drawing the graphs to ensure accurate representation.