Question

Finding the length and width of rectangles help please.

Answer 1

Page 31 7-10 help please

Answer 2

Please

Answer 3

have you read through the example? I'm not saying that that will be enough, but just curious?

Answer 4

Yes im still not getting it.

Answer 5

ok, so just to clarify, you don't understand the example either? We want to make sure to help you understand whatever is confusing.

Answer 6

i dont understand the example either.

Answer 7

ok, let me take a look at it myself. :)

Answer 8

alright thank you

Answer 9

Let's start with the basics: Do you know the formula to find the area of a rectangle?

Answer 10

So like, if I told you we have a rectangle with length = 5, and width = 2, what would the area be?

Answer 11

length times width so 10.

Answer 12

great!

Answer 13

:)

Answer 14

So, what is probably the most confusing about the questions we are looking at is that the lengths and widths are kind of weirdly stated.

Answer 15

7-10 im having trouble i understood 1-6

Answer 16

OK, good. But, for instance, in the example they tell us that "the width is 7cm less than the length"... you are probably thinking, "What on earth are they talking about?"

Answer 17

exactly i dont understand that at all

Answer 18

OK, well let's see if we can't figure out this math mystery. :)

Let's start slightly easier. Let's say that I told you the length is 10cm. Now what does the width have to be if it is "7cm less than the length?"

Answer 19

3

Answer 20

Good, so the area would be?

Answer 21

30cm

Answer 22

Excellent you are doing great! Believe it or not we are almost ready to tackle the real thing! :D

Answer 23

Thank you

Answer 24

Alright, now this time I'm going to try to be sneaky. I will say that the length is "x"cm. In other words, it's something, but I'm not telling you. :)

So, if the width is "7cm less than" whatever the length is, can you think of a way to write that down using algebra? This part is a little tricky. So if you need help let me know.

Answer 25

w=7-l?

Answer 26

L*

Answer 27

Close... very close... Let's think about the easier example, We said that L = 10, then W = 3. We figured that out by doing W = 10 - 7. Or W = L - 7 not 7 - L. Do you see that?

Answer 28

Oh yep

Answer 29

We like to think that "7cm less than L" means "7 - L" but it's actually the other way around and should be "L - 7." Like I said a little tricky. :)

Answer 30

I see :)

Answer 31

OK, so then in the example they want us to figure out what L and W actually are. Right now we just know that they are L and W = L -7, which isn't very helpful.

Answer 32

We can do this by using the area formula! Since they tell us that A = 260 and A = L * W, all we have to do is plug in L and W.

Answer 33

Now, the book uses an "x" but you don't have to use an "x" you could use an "L" if you like.

Answer 34

okay :p its just challenging over the computer aha

Answer 35

Alright

Answer 36

you bet. :)

Answer 37

haha :)

Answer 38

OK, so we just plug in what we know into the formula and get
A = L * W becomes 260 = L * (L - 7)

Answer 39

This is now a normal algebra question, which you will have to multiply and factor and do all the nasty stuff that makes math students mad. :)

Answer 40

Do you understand the algebra steps that they do in the example? If so, then we can FINALLY try one of the questions that you care about. :)

Answer 41

its quite irritating aha and yes :)

Answer 42

OK, so let's take a look at 7.

Answer 43

What do we know?

Answer 44

L x w

Answer 45

Well, we know the following:

A = 88
A = L * W
L = something
W = 3 more than L = some algebra thing

Answer 46

Oh of the problem my bad haha

Answer 47

no problem, "what do we know" is kind of a vague question. :)

Answer 48

no big deal

Answer 49

Let's focus in on that W, which is always the weird part, how can we write that algebraically?

Answer 50

In other words, let's try to translate "W is 3 more than L" into math lingo.

Answer 51

W+3=L

Answer 52

Nice try. :) Think about an actual number first to see the pattern. Suppose L were 10. If W is 3 more than that, what is W?

Answer 53

3+W=L?

Answer 54

im kinda lost im sorry aha

Answer 55

No worries, it's not easy. :)

Answer 56

:)

Answer 57

So, if L is 10cm and W is 3 more than 10cm that means that it must be 13 cm, right?

Answer 58

Yes

Answer 59

I'm just trying to use an easier question to understand what is happening. :)

Answer 60

Thanks

Answer 61

So, I ask myself, how did I get that answer for W? All I did was take W = 10 + 3.

Answer 62

But that's the same as saying W = L + 3.

Answer 63

So basically were just finding the two numbers that were multiplied

Answer 64

Yes, there's still a lot more work to be done, but we need to figure out how to write both the length and width so that we can multiply them correctly.

Answer 65

So, let's recap, where are we:

A = 88
A = L * W
L
W = L + 3

Answer 66

tryng to find the length and width

Answer 67

Right, so now, the way we are going to find them is by plugging in our information into the area formula. This gives us

88 = L * (L + 3)

Notice how this only has L in it, so when we do the algebra we will find the answer for L. But, we won't have W yet.

Answer 68

so the answer is 11,8?

Answer 69

I think i got this one.

Answer 70

Oh well, yeah, that seems to work. Obviously 11 * 8 = 88 and 11 is 3 more than 8. Congrats!

Answer 71

But, which one is the length and which one is the width?

Answer 72

width is 11 length is 8

Answer 73

good. couldn't fool you. :)

Answer 74

I think you understand the plugging in part. Do you want to quickly go through the others and translate them?

Answer 75

I appreciate it thanks can you also help with page 34 1,4

Answer 76

I got it i appreciate it though Thank you so much for your help are you familiar with graphing?

Answer 77

cool, awesome. Let me take a look before I answer that. :)

Answer 78

Alright Thank you

Answer 79

OK, yeah, these aren't too bad.

Answer 80

Im not sure how to put it in the graphing calculator that is provided

Answer 81

http://go.hrw.com/math/midma/gradecontent/manipulatives/GraphCalc/graphCalc.html heres the calculator

Answer 82

which model do you have?

Answer 83

ok, I'll check it out

Answer 84

im supposed to use an online calculator

Answer 85

Thanks

Answer 86

OK, makes sense... So let's look at number 1 first.

Answer 87

We are supposed to examine 5x^2 + 3

Answer 88

So, do you see the red "y1" at the top of the calculator?

Answer 89

yes

Answer 90

alright, next to that is an = sign and some blank stuff to fill in. We should put 5x^2 + 3 into that box.

Answer 91

let me know once you've done that

Answer 92

Alright got it

Answer 93

OK, now on the right side of the calc, sort of towards the middle is a "GRAPH" button, hit that.

Answer 94

and you should see a "smile" on the graph.

Answer 95

okay :)

Answer 96

yup

Answer 97

or maybe it's a carrot? whatever. :)