My Math Forum  

Go Back   My Math Forum > High School Math Forum > Pre-Calculus

Pre-Calculus Pre-Calculus Math Forum

Thanks Tree1Thanks
  • 1 Post By studiot
LinkBack Thread Tools Display Modes
March 25th, 2017, 01:09 PM   #1
Joined: Mar 2017
From: leuven

Posts: 20
Thanks: 0

really basic question about functions

So I recently started a highschool level math course (in my spare time, so without any teachers) on top of my high school studies,

On one of the exercises, they gave me a function,

h(x) = -|2x-5|

I have never seen brackets like this | before. I'm required to solve a bunch of things (zero, min/max. etc., really easy stuff still). I'm required to use the TI-84 plus calculater (Texas Instruments) to solve this.

So first of all I have to fill in this function in y=.

But I don't know how to input brackets like | and whether I can also get the same result by using normal brackets ().

could anyone tell me how to input those special brackets in a calculator and what the difference is between || and ()?

Thank you for your time at least.

Last edited by skipjack; March 25th, 2017 at 05:22 PM.
vlekje5 is offline  
March 25th, 2017, 01:13 PM   #2
Senior Member
romsek's Avatar
Joined: Sep 2015
From: USA

Posts: 1,944
Thanks: 1011

$|x|$ is referred to as the "absolute value" of $x$

You can think of it as stripping away the negative sign.

$|x| = \begin{cases} 0 &x=0 \\ -x &x < 0 \\ x &0 < x \end{cases}$

some info on using the absolute value on your calculator

Last edited by romsek; March 25th, 2017 at 01:23 PM.
romsek is offline  
March 25th, 2017, 01:20 PM   #3
Joined: Mar 2017
From: leuven

Posts: 20
Thanks: 0

woa thanks that really helped me!

There was no info about it in my handbook at all. now the result looks way more realistic.
vlekje5 is offline  
March 25th, 2017, 01:39 PM   #4
Senior Member
Joined: Jun 2015
From: England

Posts: 824
Thanks: 243

it is also written abs(x) in some places such as computers.

Another name is the modulus or mod(x)

You can get the vertical line symbol with the shift key and the key to the right of the z key on a computer keyboard. Thus |

Go well in your studies and if in doubt ask.

Thanks from Joppy
studiot is offline  
March 25th, 2017, 02:09 PM   #5
Senior Member
Joined: May 2016
From: USA

Posts: 1,030
Thanks: 420

Another way is

$|x| = \sqrt{x^2}.$

Means the exact same thing as what Romsek said, but it is very easy to compute on a calculator.
JeffM1 is online now  
March 25th, 2017, 03:48 PM   #6
Joined: Mar 2017
From: leuven

Posts: 20
Thanks: 0

okay didn't know about the alternative naming of mod(x)
the keyboard shortcut doesnt work for me though since i don't have the qwerty layout
tough i know how to get | it using my pc.

The course i'm following is really bad on some parts since it gives you 4 pages of information and 2 pages of practice excercises which i all get but then theyl just base the excercises on grades on things that aren't in the book and that i haven't ever seen before. will be a serious struggle but i'l do my very best to get through it.

I see it somehow makes sence since you eliminate the - by making it a square root. Though honestly i couldnt possibly guess that before since i had |absolutely| no idea what the brackets did (pun intended)
vlekje5 is offline  

  My Math Forum > High School Math Forum > Pre-Calculus

basic, functions, question

Thread Tools
Display Modes

Similar Threads
Thread Thread Starter Forum Replies Last Post
basic question john beattie New Users 1 September 17th, 2015 10:42 AM
Basic question genieboy Elementary Math 4 November 15th, 2012 03:28 AM
Basic question OriaG Linear Algebra 1 November 7th, 2012 05:21 PM
Basic question Dudewithmathproblems Algebra 12 February 6th, 2012 12:37 PM
Basic functions ka1 Math Events 1 October 19th, 2011 10:19 AM

Copyright © 2018 My Math Forum. All rights reserved.