Functions, Notation checking if i did these correct

zee-f · 2011-09-03 07:26:34

1- i choose D

1. Is this a function? Why or why not?

((((the first image ))))

A It is not a function because there are more numbers in the domain than in the range
BIt is not a function because -7 maps to both 1 and 2.
CIt is a function because each element of the domain maps to only one element of the range.
DIt is not a function because -3 doesnt map to anything.
E It is not a function because the numbers are negative

2- i choose B
2. Is this a function? Why or why not?

(( second image )))

AIt is not a function because 9 doesnt map to anything.
BIt is not a function because 12 maps to more than one element of the range.
CIt is a function because only one element maps to each element of the range.
D It is a function because each y-value maps to only one x-value.
E It is a function because 12 maps to one element of the range.

3-i choose (F)
3. Is this a function? Why or why not?
{(1, 3), (2, 4), (3, 5), (4, 7)}

AIt is not a function because 4 + 2 is not equal to 7.
BIt is not a function because (0, 0) is not included in the set of points.
C
It is not a function because the domain is not equal to the range. . DIt is a function because all of the numbers are positive.

EIt is a function because each y-value maps to only one x-value.

FIt is a function because each x-value maps to only one y-value.

4- i choose D
4. What is the domain and range of the number set in question 3?

ADomain: {3, 4, 5, 7}; Range: {1, 2, 3, 4}
BDomain: {1, 2, 3, 4}; Range: {3, 4, 5, 6}
CDomain: {1, 4}; Range: {3, 7}
DDomain: {1, 2, 3, 4}; Range: {3, 4, 5, 7}
EDomain: {3, 7}; Range: {1, 4}
FDomain: {1, 2, 3, 5}; Range: {3, 4, 6, 7}

5- i choose (A)

5. What is the domain and range of the number set{(-6, 4), (6, -4), (-6, -4), (6, 4)} ?

ADomain: {-6, 6}; Range: {-4, 4}
BDomain: {-4, 4}; Range: {-6, 6}
CDomain: {6}; Range: {-4, 4}
DDomain: {-6}; Range: {-4}
EDomain: {-6, 6}; Range: {4}
F Domain: {6}; Range: {4}

6- i choose (C)
6. What is the domain and range of the number set {(1, 1), (2, 1), (-7, 1), (21, 1)} ?

ADomain: {1}; Range: {-7, 1, 2, 21}
B Domain: {-7, 1, 2}; Range: {1}
CDomain: {-7, 1, 2, 21}; Range: {1}

anonimnystefy · 2011-09-03 07:50:24

hi zee-f

everything is absolutely correct,but i would still like for someone else to confirm!

ShivamS · 2011-09-03 08:42:31

Everything seems correct, but I may have skimmed through it a bit.

bobbym · 2011-09-03 09:34:28

Hi zee-f;

1) Is correct.

2) Is correct.

Oh I see you have a list of points.

3) Is correct.

4) Is correct.

5) Is correct.

Shivamcoder · 2011-09-03 09:48:57

bobbym, I believe none are required.

bobbym · 2011-09-03 09:55:40

Hi;

I got it now. I did not see the list in 4 and stopped right there.

Bob · 2011-09-03 19:00:50

hi zee-f and everyone,

I think all six answers are correct.

(5) is not a function but no claim is made for this, so I guess that's ok.

Well done!

Bob

Last edited by Bob (2011-09-03 19:04:08)

zee-f · 2011-09-04 01:54:54

thanx everybody

bobbym · 2011-09-04 01:58:23

Hi zee-f;

How are you doing today?

zee-f · 2011-09-04 02:19:48

hi bobbym,

am doing great how are you

zee-f · 2011-09-04 03:22:34

7- i choose B
7. Use the vertical line test to determine if the graph below represents a function. If it is not a function, tell where the vertical line test fails.

first image

AIt is a function.
BIt is not a function. The vertical line test fails when x > 0.
CIt is not a function. The graph does not extend to the left of the y-axis.
DIt is not a function. The vertical line test fails only at x = 1.

8- i choose A
8. Use the vertical line test to determine if the graph below represents a function. If it is not a function, tell where the vertical line test fails.

((second image ))

AIt is a function.

B It is not a function. The vertical line test fails when x = 0.

C It is not a function. The vertical line test fails only at x = 1.

DIt is not a function. The vertical line test fails when x > 0.

Bob · 2011-09-04 03:34:46

hi zee-f,

I like these answers only if your images are the wrong way round.

I've sometimes found this happens ... you send them in the order you want and they get reversed ... so next time you send them reversed and it displays them that way. ggggrrrr

Bob

Last edited by Bob (2011-09-04 03:36:44)

zee-f · 2011-09-04 03:56:51

oooh yeah the images are flipped around i missed that

zee-f · 2011-09-04 05:49:05

9-D

9. Find f(4) if f(x) = (1/2)x + 13

A f(4) = 4

B f(4) = 12

C f(4) = 17/2

Df(4) = 15

E f(4) = 17

F f(4) = 1

10-D
10. Find f(5) if f(x) = (3/5)x - 10

A f(5) = -5

Bf(5) = 5

Cf(5) = -25

Df(5) = -7

Ef(5) = 13

F f(5) = -13

11-b
11. Find f(-1) if f(x) = x2 + 7

Af(-1) = 9
Bf(-1) = 6
Cf(-1) = -7
Df(-1)= -9
Ef(-1) = 8
Ff(-1) = -1

12-D
12. Find f(2) if f(x) = 3x3 -12x2

Af(2) = -9
Bf(2) = -30
Cf(2) = -16
Df(2)= -24
Ef(2) = -18
Ff(2) = -2

anonimnystefy · 2011-09-04 05:59:04

hi zee-f

again all correct!

zee-f · 2011-09-04 06:00:00

thank you

zee-f · 2011-09-04 06:33:09

(that one is spouse to be a not equal sign))

13- E
13. Find the domain of
x^2 + 1/x + 1

Ax ¹ 1
Bx ¹ -1, 0, 1
Cx ¹ 0
Dx ¹ -1,1
Ex ¹ -1
Fx ¹ -2

14-A

14. Find the domain of
x^2 - 1/x + 1

Ax ¹ -1
Bx ¹ 1
Cx ¹ -2
Dx ¹ -1, 1
Ex ¹ 2
Fx ¹ 0

15-F

15. Find the domain of
x^2 - 2x - 1/x^2 - 1

Ax ¹ -1
Bx ¹ 0
Cx ¹ 1
Dx ¹ 4
Ex ¹ -2
Fx ¹ -1, 1

16-D
16. Find the domain of
x^2 + 5x + 4/x^2 + 7x + 6

Ax ¹ 4
Bx ¹ 6, -1
Cx ¹ -4
Dx ¹ -6, -1
Ex ¹ -2, -3
Fx ¹ 2, 3

Last edited by zee-f (2011-09-04 06:33:44)

Bob · 2011-09-04 06:34:52

hi zee-f

11-b
11. Find f(-1) if f(x) = x2 + 7
Af(-1) = 9
Bf(-1) = 6
Cf(-1) = -7
Df(-1)= -9
Ef(-1) = 8
Ff(-1) = -1

You need to be careful to show your functions properly. I think this is:

In which case

So that'll be answer E.

Have a look at the top post in the Help Me section. It shows how to make proper math notation using a coding language called LaTex. It's not hard to use for the sort of functions you are using and it will enable you to show squares and cubes properly. Then we can see what the question is.

Give it a try. It'll save you time in the long run.

Bob

Last edited by Bob (2011-09-04 07:03:38)

Bob · 2011-09-04 06:36:56

hi again,

I'm just looking at your latest post. Stay on line for a moment while I check them.

Bob

anonimnystefy · 2011-09-04 06:44:54

hi zee-f

for not equal sign you can get one from the top of the page:≠

as for the questions,could you explain how you got your answer for 13

Bob · 2011-09-04 06:50:51

Right. I've looked and I'm confused again by the way these are shown.

The domain is the set of values that can (legally) put put into the function. So is the value shown meant to be the value or values that cannot be put in?

Let's look at (13)

13- E
13. Find the domain of
x^2 + 1/x + 1
Ax ¹ 1
Bx ¹ -1, 0, 1
Cx ¹ 0
Dx ¹ -1,1
Ex ¹ -1
Fx ¹ -2

x squared and 1 are not restricted domain-wise.

What about 1/x ?

If x = 0 you get the function zooming off to infinity which is not considered as a number and hence x= 0 must be excluded from the domain.

So the correct way to show this is:

I'm guessing that is answer C, but I don't like the way it is shown.

Bob

Last edited by Bob (2011-09-04 07:06:41)

Bob · 2011-09-04 07:00:55

Now I'm looking at the others. Take (16)

16-D
16. Find the domain of
x^2 + 5x + 4/x^2 + 7x + 6
Ax ¹ 4
Bx ¹ 6, -1
Cx ¹ -4
Dx ¹ -6, -1
Ex ¹ -2, -3
Fx ¹ 2, 3

Do you mean

Because that is what you have written.

I think you probably meant

If so, then -6 and -1 are the values to exclude.

But, do you see why LaTex is so useful for showing the functions properly.

If you click on my LaTex code, you'll see how I did it. Just put square brackets math and square brackets /math around the code to make it work.

Bob

anonimnystefy · 2011-09-04 07:16:07

hi bob

what you said in your second post is probably true,so his answer to 13 is true as well.

it isn't x^2+1/x+1 it is x^2+1/(x+1) so the answer is -1.

hi zee-f

if what bob said is the case than all your answers are correct!

zee-f · 2011-09-04 07:16:11

hey am ganna post what i mean using the LaTex so i can be more clear of what i mean

anonimnystefy · 2011-09-04 07:20:58

that would be nice!

Math Is Fun Forum

#1 2011-09-03 07:26:34

Functions, Notation checking if i did these correct

#2 2011-09-03 07:50:24

Re: Functions, Notation checking if i did these correct

#3 2011-09-03 08:42:31

Re: Functions, Notation checking if i did these correct

#4 2011-09-03 09:34:28

Re: Functions, Notation checking if i did these correct

#5 2011-09-03 09:48:57

Re: Functions, Notation checking if i did these correct

#6 2011-09-03 09:55:40

Re: Functions, Notation checking if i did these correct

#7 2011-09-03 19:00:50

Re: Functions, Notation checking if i did these correct

#8 2011-09-04 01:54:54

Re: Functions, Notation checking if i did these correct

#9 2011-09-04 01:58:23

Re: Functions, Notation checking if i did these correct

#10 2011-09-04 02:19:48

Re: Functions, Notation checking if i did these correct

#11 2011-09-04 03:22:34

Re: Functions, Notation checking if i did these correct

#12 2011-09-04 03:34:46

Re: Functions, Notation checking if i did these correct

#13 2011-09-04 03:56:51

Re: Functions, Notation checking if i did these correct

#14 2011-09-04 05:49:05

Re: Functions, Notation checking if i did these correct

#15 2011-09-04 05:59:04

Re: Functions, Notation checking if i did these correct

#16 2011-09-04 06:00:00

Re: Functions, Notation checking if i did these correct

#17 2011-09-04 06:33:09

Re: Functions, Notation checking if i did these correct

#18 2011-09-04 06:34:52

Re: Functions, Notation checking if i did these correct

#19 2011-09-04 06:36:56

Re: Functions, Notation checking if i did these correct

#20 2011-09-04 06:44:54

Re: Functions, Notation checking if i did these correct

#21 2011-09-04 06:50:51

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#22 2011-09-04 07:00:55

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#23 2011-09-04 07:16:07

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