Absolute Value - By Anywhere Math
Transcript
00:0-1 | Welcome anywhere . Math . I'm Jeff Jacobson . And | |
00:01 | today we're gonna talk about absolute value . Let's get | |
00:05 | started . Which animal can travel farther away from sea | |
00:27 | level . A bald eagle or a whale . Alright | |
00:31 | , let's try to figure this out now . First | |
00:33 | Bald Eagles have been seen gliding at heights of up | |
00:37 | to 4500m above sea level . Now , what about | |
00:44 | the whale ? Well , it all depends on the | |
00:46 | type of whale . And the way we're going to | |
00:49 | talk about today is called the Q beer beat whale | |
01:00 | . And right there now this funny looking whale is | |
01:05 | really , really special . I just saw that it | |
01:07 | was able to dive 3000 m below sea level . | |
01:14 | This mammal holds the record for the deepest dive and | |
01:19 | the longest dive . It was underwater for over two | |
01:23 | hours . Let's draw a quick little number line because | |
01:27 | I'm talking about sea level . Instead of a horizontal | |
01:30 | number line , I'm gonna draw a vertical number line | |
01:35 | and zero is going to represent sea level . Okay | |
01:42 | , well above sea level is obviously gonna be my | |
01:45 | bald eagle . Below sea level is going to be | |
01:48 | this whale 3000 m below sea level . Now below | |
01:54 | . I'm gonna write that as negative negative 3000 . | |
01:59 | So the question is which one is farther away from | |
02:03 | sea level . Okay . Hopefully with the number line | |
02:07 | you can see that . Oh definitely the bald eagle | |
02:09 | is farther away because this distance is greater than this | |
02:14 | distance . Now when we're talking about distances away from | |
02:18 | zero , we're talking about absolute value . So let's | |
02:22 | get into absolute value . And some examples , absolute | |
02:25 | value of a number is just the distance . A | |
02:33 | number is from zero on a number line . Okay | |
02:48 | , It's the distance that number is from zero on | |
02:52 | a number line . Now , distance is really important | |
02:55 | because when you think about it , we'd never have | |
02:58 | negative distances . Right . If someone asks you , | |
03:01 | how far did you run yesterday ? You're never gonna | |
03:04 | say oh I ran negative five miles . That makes | |
03:06 | no sense . So the same thing here , when | |
03:09 | you take the absolute value of a number , you're | |
03:11 | going to get something that's positive , A distance is | |
03:14 | positive . So the way we write absolute value is | |
03:19 | with two vertical lines . So for example . Uh | |
03:23 | huh . Mm . Okay . This I would read | |
03:26 | as the absolute These two lines means the absolute value | |
03:32 | of three . Okay , the absolute value of three | |
03:36 | is three . Right ? And you can think about | |
03:40 | it , how far away from zero is three on | |
03:44 | a number line ? Well it's three away . Okay | |
03:47 | , that's why that's three . Let's get into our | |
03:49 | first example . Okay , example , number one a | |
03:52 | find the absolute value of seven . So we're talking | |
03:56 | about how far away is seven from zero on a | |
03:59 | number line . So I'm going to draw a number | |
04:01 | line . We're here at seven . The question is | |
04:07 | , what is this distance from 07 ? How far | |
04:12 | away is that ? Seven from zero ? Well I | |
04:15 | can count . Right . 1234567 . Right ? But | |
04:19 | it's pretty obvious that it is seven . Okay , | |
04:23 | seven away . So that means the absolute value . | |
04:28 | Right ? We read it like that and one quick | |
04:30 | tip . Make sure that these vertical lines are longer | |
04:34 | than your numbers . If not If you're not kind | |
04:39 | of careful it can really quickly look like 171 . | |
04:44 | Okay , so again make sure that when you write | |
04:47 | absolute value , those numbers are those vertical lines are | |
04:51 | longer than your numbers . So the absolute value of | |
04:54 | seven is seven . Okay . Let's look at b | |
04:58 | find the absolute value of negative 2.5 . Same thing | |
05:01 | . I'm gonna draw a quick number line . So | |
05:04 | negative two and one half would be halfway between negative | |
05:07 | two and negative three . So it's going to be | |
05:09 | right about there negative two and one half again . | |
05:15 | What is the distance from ? Negative 2.5 to 0 | |
05:19 | ? So from here to hear . Okay again you | |
05:25 | could count but hopefully you notice that that distance is | |
05:29 | 2.5 . It's 2.5 away in the absolute value of | |
05:33 | negative 2.5 is 2.5 positive 2.5 . Right ? These | |
05:41 | are distances . It's going to be positive . Okay | |
05:44 | ? So hopefully you notice here something , the absolute | |
05:47 | value of a positive number . Stay positive . It's | |
05:51 | a positive distance . But then when we took the | |
05:53 | absolute value of a negative number , it became positive | |
05:57 | , right ? Because distance need to be positive . | |
06:00 | Okay , here's some to try on your own . | |
06:11 | Okay . example to compare to and absolute value of | |
06:16 | -5 . Uh Well first we need to figure out | |
06:22 | what the absolute value of negative five is . Now | |
06:24 | we could draw a number line again and find our | |
06:27 | distance but hopefully you're starting to get it . How | |
06:30 | far away is negative five from zero ? Well the | |
06:34 | absolute value of negative five is five . So my | |
06:38 | answer is two is less than the absolute value of | |
06:43 | -5 . Let's look at b compare the absolute value | |
06:49 | of -4 and the absolute value of four . Well | |
06:54 | the absolute value of negative four is going to be | |
06:57 | four right ? Negative force four away from zero , | |
07:00 | that's four . uh and the absolute value of four | |
07:04 | is also for which means The absolute value of -4 | |
07:10 | is equal to the absolute value of four . Okay | |
07:18 | yeah here's some more to try on your own . | |
07:28 | Alright example three order the values from least to greatest | |
07:32 | . Uh So we have a lot of absolute values | |
07:35 | here and we've got a couple of new things we | |
07:38 | haven't talked about yet . So in order to order | |
07:41 | these , I first need to know what the value | |
07:43 | is so I need to figure out these absolute values | |
07:46 | . So first what is the absolute value of negative | |
07:49 | five ? Well that's going to be five right , | |
07:52 | it's five away from 03 is still three . The | |
07:57 | absolute value of two , that's two away from zero | |
08:00 | . So that is to now here notice where the | |
08:05 | negative sign is . Okay it's not inside the absolute | |
08:09 | value , it's on the outside . So we would | |
08:11 | read this as the negative absolute value of three . | |
08:16 | So first what you need to do is just find | |
08:18 | the absolute value of three and then you add your | |
08:22 | negative after that . So the absolute value of three | |
08:26 | is 3 . Then we put the negative sign in | |
08:29 | front so we get -3 . Last one here The | |
08:35 | negative absolute value of -4 . So again ignore this | |
08:41 | negative for a second and let's concentrate on the absolute | |
08:44 | value . The absolute value of negative for is four | |
08:48 | . Right ? Negative four is far away from zero | |
08:52 | but then we put a negative in front so this | |
08:54 | becomes negative four . Okay ? So now if we're | |
09:00 | gonna order these obviously my negative four is the least | |
09:05 | which means this Is the least . So the negative | |
09:08 | absolute value of -4 . His first then they get | |
09:13 | three here so that's Negative Absolute Value of three . | |
09:18 | Then we've got to which was absolute value of two | |
09:22 | . Then we've got three which is just three . | |
09:26 | And finally the greatest is gonna be the absolute value | |
09:30 | of negative five . So there is my order from | |
09:37 | least to greatest . Okay , here's some more to | |
09:40 | try on your own as always , thank you so | |
09:47 | much for watching and if you like this video , | |
09:49 | please subscribe . |
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