# 1.4 Homework: functions in the real world

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This module provides practice problems designed to mimic real life applications of functions.

Laura is selling doughnuts for 35¢ each. Each customer fills a box with however many doughnuts he wants, and then brings the box to Laura to pay for them. Let n represent the number of doughnuts in a box, and let $c$ represent the cost of the box (in cents).

• If the box has 3 doughnuts, how much does the box cost?
• If $c=\text{245}$ , how much does the box cost? How many doughnuts does it have?
• If a box has n doughnuts, how much does it cost?
• Write a function $c\left(n\right)$ that gives the cost of a box , as a function of the number of doughnuts in the box.

Worth is doing a scientific study of graffiti in the downstairs boy’s room. On the first day of school, there is no graffiti. On the second day, there are two drawings. On the third day, there are four drawings. He forgets to check on the fourth day, but on the fifth day, there are eight drawings. Let d represent the day, and g represent the number of graffiti marks that day.

• Fill in the following table, showing Worth’s four data points.  d (day) g (number of graffiti marks)
• If this pattern keeps up, how many graffiti marks will there be on day 10?
• If this pattern keeps up, on what day will there be 40 graffiti marks?
• Write a function $g\left(d\right)$ ) that gives the number of graffiti marks as a function of the day .

Each of the following is a set of points. Next to each one, write “yes” if that set of points could have been generated by a function, and “no” if it could not have been generated by a function. (You do not have to figure out what the function is. But you may want to try for fun—I didn’t just make up numbers randomly…)

• $\left(1,-1\right)\left(3,-3\right)\left(-1,-1\right)\left(-3,-3\right)$ ________
• $\left(1,\pi \right)\left(3,\pi \right)\left(9,\pi \right)\left(\pi ,\pi \right)$ ________
• $\left(1,1\right)\left(-1,1\right)\left(2,4\right)\left(-2,4\right)\left(3,9\right)\left(-3,9\right)$ ________
• $\left(1,1\right)\left(1,-1\right)\left(4,2\right)\left(4,-2\right)\left(9,3\right)\left(9,-3\right)$ ________
• $\left(1,1\right)\left(2,3\right)\left(3,6\right)\left(4,\text{10}\right)$ ________

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

• $f\left(2\right)=$
• $f\left(-1\right)=$
• $f\left(\frac{3}{2}\right)=$
• $f\left(y\right)=$
• $f\left(\text{spaghetti}\right)=$
• $f\left(\sqrt{x}\right)$
• $f\left(f\left(x\right)\right)$

Make up a function that has something to do with movies .

• Think of a scenario where there are two numbers, one of which depends on the other. Describe the scenario, clearly identifying the independent variable and the dependent variable .
• Write the function that shows how the dependent variable depends on the independent variable.
• Now, plug in an example number to show how it works.

#### Questions & Answers

what is the stm
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
How can I make nanorobot?
Lily
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
how can I make nanorobot?
Lily
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
how did you get the value of 2000N.What calculations are needed to arrive at it
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