Math Is Fun Forum

Lpravia020614

Member

Registered: 2015-11-03

Posts: 35

Piece wise functions

Can someone please help me, i am almost done with this class except for this lesson!

1.  Write a piecewise function for the graph

http://www.sc.whitmoreschool.org/sec/classes/images/1995/piecewisegraph2.jpg

2. On your own paper, draw a graph to represent the total cost of the locker and the time. Then answer the questions.

If you are a member of Buff Up Gym, you can rent a locker by the hour.  The cost is $2.00 per hour.

a.       Is this a piecewise function?  Why or why not?

b.      What would the total cost be to rent a locker for 3 hours and 15 minutes?

c.       Write an equation for this function.

Relentless

Member

Registered: 2015-12-15

Posts: 631

Re: Piece wise functions

Hello!

2. a. It is not, because they ask for one equation in 2c. Bit of a giveaway (:

2. b. $2 per hour for 3.25 hours. See 2c.

2. c. The cost in dollars is double the time in hours.

For question 1, I personally hate eyeballing graphs and having to say "well it looks to be around about such and such sort of maybe". Points are much more convenient. But one way of solving it is by using the formulas y = mx + b and m = (y2-y1)/(x2-x1) and the endpoints of the lines.
For example, the last line looks to me to extend from (2,3) to (7,-2). The slope (m) is (-2-3)/(7-2) = -1. That is the change in y for each increase of +1 of x. To find the y-intercept (b) use this relation to find y when x=0. The last condition is y = -x + 5 after x=2.

Lpravia020614

Member

Registered: 2015-11-03

Posts: 35

Re: Piece wise functions

Thank you for the help.
for 2c it has to be in equation form, how would i do that ( like variable wise)

For #1 you kind of confused me..

JuNeBuG629

Member

Registered: 2016-04-20

Posts: 1

Re: Piece wise functions

I'm in Whitmore too! Is there anyway you can email me the answers for these questions?

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Piece wise functions

What is wrong with them being posted right here in the forum?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

thickhead

Member

Registered: 2016-04-16

Posts: 1,086

Re: Piece wise functions

It is a piecewise function.

equation can be written in the form
rent=2*int (t+0.9999)  where int() is the function "integer part of ".
I wanted to make it int(t+1) but at time cross over it gives rise to problem e.g. int(t+1) gives value of 3 when t=2 exactly in which case charge will be for 3 hours but int(t+0.9999) will give the correct value of 2.

Last edited by thickhead (2016-04-20 16:26:09)

---

{1}Vasudhaiva Kutumakam.{The whole Universe is a family.}
(2)Yatra naaryasthu poojyanthe Ramanthe tatra Devataha
{Gods rejoice at those places where ladies are respected.}