Algebraic Expressions (Advanced) - By Anywhere Math
Transcript
00:0-1 | Welcome to anywhere , Math . I'm Jeff , Jacobson | |
00:01 | and today we're learning all about algebraic expressions . Let's | |
00:06 | get started . Alright before we get to our first | |
00:26 | example , let's talk a little bit about the vocabulary | |
00:29 | involved with algebraic expressions . The algebraic part means that | |
00:33 | we're gonna have variables in the expressions and then because | |
00:36 | their expressions means there's gonna be no equal sign right | |
00:39 | . If it had an equal sign then we'd be | |
00:41 | talking about equations . But for today just algebraic expressions | |
00:45 | . Now , the first word we're going to talk | |
00:48 | about our terms in terms are the parts of an | |
00:52 | expression and algebraic expression . Not the operations . Next | |
00:56 | life terms are terms that have the same variables but | |
01:00 | also raise the same exponents . If you have an | |
01:03 | X and A Y . Those are not like terms | |
01:06 | because there not the same variables . If you had | |
01:10 | an X squared and X cubed . Well those are | |
01:14 | the same variables but they're not raised the same exponents | |
01:17 | . So they also would not be like terms , | |
01:20 | Okay , last word is constant terms . Or just | |
01:24 | constants . And constants are also like terms but they | |
01:27 | have no variables . They're called constants because no matter | |
01:30 | what the value of the variables are , they stay | |
01:33 | constant , they stay the same . Now let's get | |
01:36 | into our first example example one identify the terms and | |
01:39 | the like terms in each expression . So for a | |
01:42 | we've got nine x minus two plus seven minus x | |
01:47 | . So again , this is an algebraic expression because | |
01:50 | we have variables . Uh And then first thing I'm | |
01:54 | gonna do is I'm going to identify the terms well | |
01:57 | to do that . What I want to do first | |
01:59 | is change this into strictly an addition expression . So | |
02:04 | whenever I have subtraction , I'm going to change that | |
02:07 | to addition , adding the opposite . I'm gonna rewrite | |
02:10 | this as nine X . Instead of minus two , | |
02:14 | I'm gonna say plus a negative to . Uh and | |
02:17 | then plus seven . That's ok . And then instead | |
02:19 | of minus X , you probably could guess it plus | |
02:23 | negative eggs . So my first step is just to | |
02:27 | rewrite uh the expression as an addition expression . Now | |
02:32 | I'm ready to identify the terms . And again the | |
02:34 | terms are the parts of the expression without the operations | |
02:40 | . So the terms then are nine X . Negative | |
02:43 | 27 and negative X . Those are my terms . | |
02:48 | My life terms are where I have the same variables | |
02:53 | raised to the same exponents or constants . I have | |
02:57 | a nine X . And a negative X . They're | |
02:59 | both X . It doesn't matter that this is negative | |
03:02 | . That's okay . The fact is that both of | |
03:04 | these are raised to the first power . Even though | |
03:07 | we don't write it , there's just one X . | |
03:09 | Okay so those are like terms nine X . And | |
03:13 | negative X . I'll put a comma my other group | |
03:17 | of like terms are my constant negative two and 78 | |
03:21 | of two and seven . Ok . Part B . | |
03:25 | I'm gonna do slightly different . Um I could do | |
03:28 | the same thing and just change it first to an | |
03:30 | addition expression again . But I'm gonna circle . And | |
03:35 | this is another strategy that a lot of students like | |
03:38 | to use . You just circle the parts of the | |
03:41 | expression . And if you see a negative or a | |
03:44 | subtraction in this case right now you include that with | |
03:48 | whatever is after it . So I'm gonna use that | |
03:50 | strategy here . So I have W squared . Whenever | |
03:53 | I see A plus , I'm not going to circle | |
03:55 | that I have a five W . I have minus | |
03:59 | three W squared . So I'm gonna circle . When | |
04:02 | I see that subtraction , I'm going to include that | |
04:04 | with what comes after it . And then I'm going | |
04:07 | to have that w Now I want you to see | |
04:10 | how it's similar to what we did here . If | |
04:11 | I changed this expression too . Uh In addition expression | |
04:15 | , this is what I would get , I would | |
04:17 | get W squared plus five W . And then remember | |
04:21 | subtraction , we would change that to plus a negative | |
04:25 | three W squared . And then plus W . Again | |
04:28 | notice my terms , W Square W squared . Five | |
04:32 | W . Five W . Negative three W squared , | |
04:35 | negative three W squared W . And W . So | |
04:39 | a lot of students like to use this and if | |
04:42 | that works for you , then great . So let's | |
04:44 | list our terms . We have W squared five W | |
04:49 | . Uh negative three W squared . And w now | |
04:55 | let's do our like terms . So again , we're | |
04:57 | looking if you notice they're all w . But then | |
05:00 | we also have to check to make sure they have | |
05:02 | the same exponents . So I've got W squared here | |
05:05 | and a negative three W squared here . It doesn't | |
05:08 | matter with this coefficient . That's okay . These are | |
05:11 | still like terms because there w squares . Uh So | |
05:16 | that's my first W square it and native three W | |
05:21 | squared . And then we've got five W and W | |
05:23 | . Again the coefficient is okay , We're just looking | |
05:27 | at the same variable in this case , the race | |
05:30 | to the first power . So 5W&W . Those are | |
05:34 | my other like terms . Let's look at another example | |
05:39 | . Alright example , to simplify 3/4 Y plus 12 | |
05:43 | minus one half Y minus six . Okay , well | |
05:47 | first I know how to simplify fractions , right to | |
05:50 | six would become one third . But what about simplifying | |
05:54 | algebraic expressions ? How do I know when it's in | |
05:58 | simplest form ? When there are no like terms and | |
06:02 | no parenthesis ? When you get to that point , | |
06:06 | then you've simplified it far enough . It's in simplest | |
06:09 | form . And to get there we call it combining | |
06:12 | like terms . So what we just identified when you | |
06:15 | see like terms , we can combine them . Um | |
06:18 | and use the distributive property when you need to . | |
06:20 | That's gonna help you get rid of the parentheses . | |
06:22 | So let's try example to I'm going to change it | |
06:25 | to an addition expression . So this is gonna become | |
06:29 | 3/4 . Why ? Plus 12 ? That's already addition | |
06:33 | . This minus is gonna be plus a negative one | |
06:37 | half Why ? And then that minus six becomes plus | |
06:41 | negative six . And the reason we do that is | |
06:43 | because now I can change the order . The community | |
06:46 | of property of addition means I can change the order | |
06:48 | around because I have all addition . So I'm gonna | |
06:51 | rewrite it 3/4 . Why switch this around ? Plus | |
06:56 | negative one half , y plus 12 . And then | |
07:00 | plus by negative six . Now we're ready to combine | |
07:06 | like terms . This would become negative to uh force | |
07:10 | why ? That's the same thing . So when I | |
07:13 | add that with 3/4 wide , that would give me | |
07:15 | 1/4 Y plus 12 and negative six . We become | |
07:21 | six at this point . Are there any like terms | |
07:26 | ? No , that's a constant and that has a | |
07:28 | variable of why they're not like terms . Are there | |
07:31 | any parentheses , nope . Which means this expression here | |
07:37 | is now in simplest form . Here's some to try | |
07:41 | on your own . All right , for the last | |
07:48 | example simplify this expression Now again to get it in | |
07:53 | simplest form we're looking for No like terms and no | |
07:56 | parentheses . And to get there we combine like terms | |
07:59 | and use the distributive property when necessary . Whenever you | |
08:02 | have parentheses . First thing to always look for and | |
08:06 | if you want to put a big star next to | |
08:07 | this , see if you can simplify in the parentheses | |
08:10 | first 16 plus four I can't they're not like terms | |
08:14 | . So that's okay . So now here hopefully you | |
08:17 | recognize you're gonna use that distributive property and if you | |
08:21 | don't remember how to do that , check out this | |
08:23 | video but we're going to distribute this negative one half | |
08:26 | to everything inside the parentheses first . So negative one | |
08:29 | half times six N . Negative one half times four | |
08:33 | negative one half times six . N plus negative one | |
08:37 | half times four . And then we still have that | |
08:41 | plus to end . Make sure you always show your | |
08:44 | work going down nice and organized . Now we just | |
08:47 | start to simplify negative one half times six . N | |
08:50 | . That's gonna be negative three N . Plus negative | |
08:53 | one half times four is gonna be negative too . | |
08:57 | And then I still have that too in now here | |
09:00 | let's combine like terms . Well negative two is the | |
09:03 | only constant . So that's going to be off by | |
09:05 | itself negative three in And to end our like terms | |
09:10 | , they're both just end and they're both just to | |
09:12 | the first power negative three . End plus to end | |
09:15 | would be negative one end which I'll just write it | |
09:19 | just negative end plus negative two . Lastly remember we | |
09:24 | can't have parentheses . So at this situation I know | |
09:28 | it's kind of weird because we we typically like to | |
09:31 | have addition . I'm going to change it back to | |
09:34 | a subtraction problem . So this becomes negative end -2 | |
09:40 | . There are no like terms and there's no parenthesis | |
09:43 | anymore . So this is in simplest form here's some | |
09:46 | more to try on your own as always . Thank | |
09:54 | you so much for watching and if you like this | |
09:56 | video please subscribe . Yeah . |
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