# 1.7 Inverse functions  (Page 9/10)

 Page 9 / 10

$f\left(x\right)=|x-5|$

$f\left(x\right)=-|x-3|$

$f\left(x\right)=|2x-4|$

For the following exercises, solve the absolute value equation.

$|x+4|=18$

$|\frac{1}{3}x+5|=|\frac{3}{4}x-2|$

For the following exercises, solve the inequality and express the solution using interval notation.

$|3x-2|<7$

$\left(-\frac{5}{3},3\right)$

$|\frac{1}{3}x-2|\le 7$

## Inverse Functions

For the following exercises, find for each function.

$f\left(x\right)=9+10x$

$f\left(x\right)=\frac{x}{x+2}$

${f}^{-1}\left(x\right)=\frac{-2x}{x-1}$

For the following exercise, find a domain on which the function is one-to-one and non-decreasing. Write the domain in interval notation. Then find the inverse of restricted to that domain.

$f\left(x\right)={x}^{2}+1$

Given $f\left(x\right)={x}^{3}-5$ and $g\left(x\right)=\sqrt[3]{x+5}:$

1. Find and $g\left(f\left(x\right)\right).$
2. What does the answer tell us about the relationship between $f\left(x\right)$ and $g\left(x\right)?$
1. and $g\left(f\left(x\right)\right)=x.$
2. This tells us that $f$ and $g$ are inverse functions

For the following exercises, use a graphing utility to determine whether each function is one-to-one.

$f\left(x\right)=\frac{1}{x}$

The function is one-to-one.

$f\left(x\right)=-3{x}^{2}+x$

The function is not one-to-one.

If $f\left(5\right)=2,$ find ${f}^{-1}\left(2\right).$

$5$

If $f\left(1\right)=4,$ find ${f}^{-1}\left(4\right).$

## Practice test

For the following exercises, determine whether each of the following relations is a function.

$y=2x+8$

The relation is a function.

$\left\{\left(2,1\right),\left(3,2\right),\left(-1,1\right),\left(0,-2\right)\right\}$

For the following exercises, evaluate the function $\text{\hspace{0.17em}}f\left(x\right)=-3{x}^{2}+2x\text{\hspace{0.17em}}$ at the given input.

$f\left(-2\right)$

−16

$\text{\hspace{0.17em}}f\left(a\right)\text{\hspace{0.17em}}$

Show that the function $\text{\hspace{0.17em}}f\left(x\right)=-2{\left(x-1\right)}^{2}+3\text{\hspace{0.17em}}$ is not one-to-one.

The graph is a parabola and the graph fails the horizontal line test.

Write the domain of the function $\text{\hspace{0.17em}}f\left(x\right)=\sqrt{3-x}\text{\hspace{0.17em}}$ in interval notation.

Given $\text{\hspace{0.17em}}f\left(x\right)=2{x}^{2}-5x,\text{\hspace{0.17em}}$ find $\text{\hspace{0.17em}}f\left(a+1\right)-f\left(1\right).$

$2{a}^{2}-a$

Graph the function

Find the average rate of change of the function $\text{\hspace{0.17em}}f\left(x\right)=3-2{x}^{2}+x\text{\hspace{0.17em}}$ by finding $\text{\hspace{0.17em}}\frac{f\left(b\right)-f\left(a\right)}{b-a}.$

$-2\left(a+b\right)+1$

For the following exercises, use the functions to find the composite functions.

$\left(g\circ f\right)\left(x\right)$

$\left(g\circ f\right)\left(1\right)$

$\sqrt{2}$

Express $\text{\hspace{0.17em}}H\left(x\right)=\sqrt[3]{5{x}^{2}-3x}\text{\hspace{0.17em}}$ as a composition of two functions, $\text{\hspace{0.17em}}f\text{\hspace{0.17em}}$ and $\text{\hspace{0.17em}}g,\text{\hspace{0.17em}}$ where $\text{\hspace{0.17em}}\left(f\circ g\right)\left(x\right)=H\left(x\right).$

For the following exercises, graph the functions by translating, stretching, and/or compressing a toolkit function.

$f\left(x\right)=\sqrt{x+6}-1$

$f\left(x\right)=\frac{1}{x+2}-1$

For the following exercises, determine whether the functions are even, odd, or neither.

$f\left(x\right)=-\frac{5}{{x}^{2}}+9{x}^{6}$

$\text{even}$

$f\left(x\right)=-\frac{5}{{x}^{3}}+9{x}^{5}$

$f\left(x\right)=\frac{1}{x}$

$\text{odd}$

Graph the absolute value function $\text{\hspace{0.17em}}f\left(x\right)=-2|x-1|+3.$

Solve $|2x-3|=17.$

$x=-7\text{\hspace{0.17em}}$ and $\text{\hspace{0.17em}}x=10$

Solve $\text{\hspace{0.17em}}-|\frac{1}{3}x-3|\ge 17.\text{\hspace{0.17em}}$ Express the solution in interval notation.

For the following exercises, find the inverse of the function.

$f\left(x\right)=3x-5$

${f}^{-1}\left(x\right)=\frac{x+5}{3}$

$f\left(x\right)=\frac{4}{x+7}$

For the following exercises, use the graph of $\text{\hspace{0.17em}}g\text{\hspace{0.17em}}$ shown in [link] .

On what intervals is the function increasing?

On what intervals is the function decreasing?

Approximate the local minimum of the function. Express the answer as an ordered pair.

$\left(1.1,-0.9\right)$

Approximate the local maximum of the function. Express the answer as an ordered pair.

For the following exercises, use the graph of the piecewise function shown in [link] .

Find $\text{\hspace{0.17em}}f\left(2\right).$

$f\left(2\right)=2$

Find $\text{\hspace{0.17em}}f\left(-2\right).$

Write an equation for the piecewise function.

$f\left(x\right)=\left\{\begin{array}{c}|x|\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{if}\text{\hspace{0.17em}}\text{\hspace{0.17em}}x\le 2\\ 3\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{\hspace{0.17em}}\text{if}\text{\hspace{0.17em}}\text{\hspace{0.17em}}x>2\end{array}$

For the following exercises, use the values listed in [link] .

 $x$ $F\left(x\right)$ 0 1 1 3 2 5 3 7 4 9 5 11 6 13 7 15 8 17

Find $\text{\hspace{0.17em}}F\left(6\right).$

Solve the equation $\text{\hspace{0.17em}}F\left(x\right)=5.$

$x=2$

Is the graph increasing or decreasing on its domain?

Is the function represented by the graph one-to-one?

yes

Find $\text{\hspace{0.17em}}{F}^{-1}\left(15\right).$

Given $\text{\hspace{0.17em}}f\left(x\right)=-2x+11,\text{\hspace{0.17em}}$ find $\text{\hspace{0.17em}}{f}^{-1}\left(x\right).$

${f}^{-1}\left(x\right)=-\frac{x-11}{2}$

So a horizontal compression by factor of 1/2 is the same as a horizontal stretch by a factor of 2, right?
The center is at (3,4) a focus is at (3,-1), and the lenght of the major axis is 26
The center is at (3,4) a focus is at (3,-1) and the lenght of the major axis is 26 what will be the answer?
Rima
I done know
Joe
What kind of answer is that😑?
Rima
I had just woken up when i got this message
Joe
Rima
i have a question.
Abdul
how do you find the real and complex roots of a polynomial?
Abdul
@abdul with delta maybe which is b(square)-4ac=result then the 1st root -b-radical delta over 2a and the 2nd root -b+radical delta over 2a. I am not sure if this was your question but check it up
Nare
This is the actual question: Find all roots(real and complex) of the polynomial f(x)=6x^3 + x^2 - 4x + 1
Abdul
@Nare please let me know if you can solve it.
Abdul
I have a question
juweeriya
hello guys I'm new here? will you happy with me
mustapha
The average annual population increase of a pack of wolves is 25.
how do you find the period of a sine graph
Period =2π if there is a coefficient (b), just divide the coefficient by 2π to get the new period
Am
if not then how would I find it from a graph
Imani
by looking at the graph, find the distance between two consecutive maximum points (the highest points of the wave). so if the top of one wave is at point A (1,2) and the next top of the wave is at point B (6,2), then the period is 5, the difference of the x-coordinates.
Am
you could also do it with two consecutive minimum points or x-intercepts
Am
I will try that thank u
Imani
Case of Equilateral Hyperbola
ok
Zander
ok
Shella
f(x)=4x+2, find f(3)
Benetta
f(3)=4(3)+2 f(3)=14
lamoussa
14
Vedant
pre calc teacher: "Plug in Plug in...smell's good" f(x)=14
Devante
8x=40
Chris
Explain why log a x is not defined for a < 0
the sum of any two linear polynomial is what
Momo
how can are find the domain and range of a relations
the range is twice of the natural number which is the domain
Morolake
A cell phone company offers two plans for minutes. Plan A: $15 per month and$2 for every 300 texts. Plan B: $25 per month and$0.50 for every 100 texts. How many texts would you need to send per month for plan B to save you money?
6000
Robert
more than 6000
Robert
For Plan A to reach $27/month to surpass Plan B's$26.50 monthly payment, you'll need 3,000 texts which will cost an additional \$10.00. So, for the amount of texts you need to send would need to range between 1-100 texts for the 100th increment, times that by 3 for the additional amount of texts...
Gilbert
...for one text payment for 300 for Plan A. So, that means Plan A; in my opinion is for people with text messaging abilities that their fingers burn the monitor for the cell phone. While Plan B would be for loners that doesn't need their fingers to due the talking; but those texts mean more then...
Gilbert
can I see the picture
How would you find if a radical function is one to one?
how to understand calculus?
with doing calculus
SLIMANE
Thanks po.
Jenica
Hey I am new to precalculus, and wanted clarification please on what sine is as I am floored by the terms in this app? I don't mean to sound stupid but I have only completed up to college algebra.
I don't know if you are looking for a deeper answer or not, but the sine of an angle in a right triangle is the length of the opposite side to the angle in question divided by the length of the hypotenuse of said triangle.
Marco
can you give me sir tips to quickly understand precalculus. Im new too in that topic. Thanks
Jenica
if you remember sine, cosine, and tangent from geometry, all the relationships are the same but they use x y and r instead (x is adjacent, y is opposite, and r is hypotenuse).
Natalie
it is better to use unit circle than triangle .triangle is only used for acute angles but you can begin with. Download any application named"unit circle" you find in it all you need. unit circle is a circle centred at origine (0;0) with radius r= 1.
SLIMANE
What is domain
johnphilip
the standard equation of the ellipse that has vertices (0,-4)&(0,4) and foci (0, -15)&(0,15) it's standard equation is x^2 + y^2/16 =1 tell my why is it only x^2? why is there no a^2?