An introduction to exponents and indices - By tecmath
Transcript
00:02 | Good day . Welcome to this series of videos looking | |
00:04 | at indices and crimes in this particular series . What | |
00:07 | we're going to have a look at first off today | |
00:09 | is indices . Then we're going to have a look | |
00:11 | at prime numbers and composite numbers . We're going to | |
00:14 | then move onto squares and square roots and then cubes | |
00:17 | and cube roots in this particular lesson . What we're | |
00:20 | going to have a look at is index notation . | |
00:22 | So industries are very useful in everyday life because what | |
00:25 | they do is they allow us to write very big | |
00:27 | numbers and very small numbers a whole lot more simply | |
00:30 | . And these come up say you are looking at | |
00:32 | our large distances or very , very , very small | |
00:35 | distances . So the distance from here to our very | |
00:37 | far away star or even how big a bacteria or | |
00:41 | something was . Because these numbers get very big and | |
00:44 | very small . We can look at significant numbers by | |
00:47 | using index notation . And what they then allows us | |
00:50 | to do is it makes the calculations a whole lot | |
00:52 | easier . So first off indices . So industries are | |
00:57 | also called exponents orders or powers and pretty much what | |
01:01 | they are , is they are repeated multiplication . There | |
01:03 | a way of writing repeated multiplication . So let me | |
01:07 | give you an example of this . Say we had | |
01:09 | two times two times two . The way that we | |
01:13 | could write this in index form is as follows , | |
01:15 | we could right 2 to the power of three . | |
01:19 | So what have we got here ? We have two | |
01:20 | particular partier , the two which has been multiplied by | |
01:23 | itself . This is called the base . We have | |
01:27 | this part up here which is how many times to | |
01:31 | has been multiplied by itself . And this is either | |
01:33 | called the index or the exponents or the power . | |
01:37 | Something like this . Okay , so you've got two | |
01:40 | parts here and that's fairly simple . Right ? So | |
01:42 | what about we have a look at one more example | |
01:44 | of this ? What about we have five times five | |
01:47 | times five times five Times five times 5 . So | |
01:53 | this is equal to , well , what's the base | |
01:56 | here ? The base which is the number which has | |
01:58 | been multiplied by itself . So the base as you | |
02:00 | can see here is five . So we have five | |
02:04 | . Now we look at how many fires have been | |
02:06 | multiplied here . We have 123456 This is five to | |
02:13 | the power of six . So it's pretty simple . | |
02:16 | Right ? Let's have a look at a couple of | |
02:18 | further examples . Okay , a bit harder . Now | |
02:21 | say we were to have three to the power of | |
02:23 | four and we would multiply this by three to the | |
02:26 | power of three . What would this be equal to | |
02:30 | ? So we can work this out . Three to | |
02:32 | the power of four here is equal to three times | |
02:36 | three times three times three . And we're multiplying this | |
02:41 | boy three to the power of three . So this | |
02:43 | is three times three times three . And as you | |
02:47 | see here , we're multiplying these two sets of numbers | |
02:49 | . So what does this leave us with ? Well | |
02:51 | , pretty simply . What base have we got ? | |
02:53 | We have a base here of three . How many | |
02:57 | times is it being multiplied by itself ? 1234567 This | |
03:02 | is three to the power of seven . So you | |
03:05 | might look at a bit of a short cut here | |
03:06 | and say , hey , what we did here is | |
03:08 | we could just go through and add these two numbers | |
03:11 | together . So this is three and this is four | |
03:13 | plus three . What about this ? Say we were | |
03:16 | in brackets to have this where we're going to go | |
03:18 | four squared to the power of three . And what | |
03:22 | is this equal to ? So what we could do | |
03:25 | is we could go through and we're working this out | |
03:27 | and we could say , okay , what we have | |
03:29 | here is four squared four squared is four times 44 | |
03:33 | multiplied by itself twice . And we're doing this three | |
03:36 | times . So we have four times four . We | |
03:39 | have four times four And we have four times 4 | |
03:43 | . Okay , Because this whole part here has been | |
03:46 | raised to this power and we're multiplying these guys . | |
03:49 | So what's our answer here ? This is equal to | |
03:52 | ? Well , our base is for and we're multiplying | |
03:56 | it by itself 123456 times . Okay . One last | |
04:03 | example . What about this ? What about we go | |
04:06 | three times four squared and see what this is equal | |
04:11 | to . So if we were to do this once | |
04:13 | , you can see is you can say , okay | |
04:14 | , what we have here is we have three times | |
04:17 | for and we're multiplying this by three times four . | |
04:22 | So if we were to do this , what do | |
04:23 | we end up with ? Well , we end up | |
04:25 | with three times four times three times four . Now | |
04:32 | , how can we write this a lot more simply | |
04:35 | ? Well , we have this number here , which | |
04:36 | is a base three . So we have two of | |
04:39 | those . So it's three multiplied by itself two times | |
04:43 | to this . We're multiplying four base , which has | |
04:47 | also got to lots here . So four squared . | |
04:50 | So , another way of writing three times four in | |
04:53 | brackets squared is three squared times four squared . Anyway | |
04:58 | , hopefully that some help of you and we'll get | |
05:01 | on very soon to the next idea which is going | |
05:02 | to be having a look at prime numbers . All | |
05:04 | right , see you . |
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