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#1 2017-04-04 20:32:44

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 746

Function and limit mcq

X^2+y^2=4    is function or not a function
Question 2 The function f(x)=ax^2+bx+x has Maximum value if        a>0  ,a <0, a>1,a>2
Question 3 The linear function f(x)=ax+b is identity function if a=b=0,  a=b=1, (a=1,b=0)

Last edited by Zeeshan 01 (2017-04-04 21:09:54)


Malik

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#2 2017-04-04 21:13:30

iamaditya
Member
From: Planet Mars
Registered: 2016-11-15
Posts: 821

Re: Function and limit mcq

X^2+y^2=4    is function or not a function

It is a functiion.

Question 2 The function f(x)=ax^2+bx+x has Maximum value if        a>0  ,a <0, a>1,a>2

Hmm, you need to find the max. and min. value of a quadratic equation. The max value of a quadratic equation is as follows:

a>0-∞
a<0--D/4a
a>1-∞
a>2-∞

Question 3

???


Practice makes a man perfect.
There is no substitute to hard work
All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

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#3 2017-04-04 21:14:34

iamaditya
Member
From: Planet Mars
Registered: 2016-11-15
Posts: 821

Re: Function and limit mcq

Question 3 The linear function f(x)=ax+b is identity function if a=b=0,  a=b=1, (a=1,b=0)

What is the question here?


Practice makes a man perfect.
There is no substitute to hard work
All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

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#4 2017-04-04 21:15:50

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Function and limit mcq

Hi;

Is that not a circle?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#5 2017-04-04 21:19:40

iamaditya
Member
From: Planet Mars
Registered: 2016-11-15
Posts: 821

Re: Function and limit mcq

No, I think.


Practice makes a man perfect.
There is no substitute to hard work
All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

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#6 2017-04-04 21:27:50

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Function and limit mcq

x^2 + y^2 = 4 I meant.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#7 2017-04-04 21:36:27

iamaditya
Member
From: Planet Mars
Registered: 2016-11-15
Posts: 821

Re: Function and limit mcq

Yeah, that is the equation of a circle. You are right, bumpkin.


Practice makes a man perfect.
There is no substitute to hard work
All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

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#8 2017-04-04 21:41:30

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Function and limit mcq

You will have to explain to him why it is a function even though it fails the vertical line test.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#9 2017-04-04 21:46:31

iamaditya
Member
From: Planet Mars
Registered: 2016-11-15
Posts: 821

Re: Function and limit mcq

A function is an expression of a variable or a relation between 2 variables.


Practice makes a man perfect.
There is no substitute to hard work
All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

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#10 2017-04-04 21:50:04

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Function and limit mcq

Hi;

Watch this video to get a bit more:

https://www.youtube.com/watch?v=Lv8Bt9Z1ohM


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#11 2017-04-04 21:52:10

iamaditya
Member
From: Planet Mars
Registered: 2016-11-15
Posts: 821

Re: Function and limit mcq

Hmm, good video...but I knew what is a function.


Practice makes a man perfect.
There is no substitute to hard work
All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

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#12 2017-04-04 21:53:00

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Function and limit mcq

It says that is not a function.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#13 2017-04-04 21:58:13

iamaditya
Member
From: Planet Mars
Registered: 2016-11-15
Posts: 821

Re: Function and limit mcq

Why isn't it a function. It is a function of x with degree 2.


Practice makes a man perfect.
There is no substitute to hard work
All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

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#14 2017-04-04 21:58:22

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,432
Website

Re: Function and limit mcq

Bobbym is right: it isn't a function. Formally, a function is a rule which uniquely maps an element of its domain to an element of its image. In other words, if
and
are sets, then
is a function if for any
, there is a unique
such that
. You can clearly see that that isn't the case here: look at where
gets mapped to, for instance.

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#15 2017-04-04 21:58:58

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Function and limit mcq

Hi;

That is not the definition of a function. You are describing an equation.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#16 2017-04-04 22:00:54

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,432
Website

Re: Function and limit mcq

Moreover, that is precisely what the point of the vertical line test is: a function can be many-to-one, but it can never be one-to-many, which the circle is.

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#17 2017-04-04 22:03:03

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,432
Website

Re: Function and limit mcq

Zeeshan 01 wrote:

Question 3 The linear function f(x)=ax+b is identity function if a=b=0,  a=b=1, (a=1,b=0)

Said differently, for which
do we have
?

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#18 2017-04-04 22:03:53

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Function and limit mcq

I would say it is not a function but some people are arguing that a circle is just two semicircles thrown together and both of the semicircles are functions. But when it comes to the equation x^2 + y^2 = 4 I would say it is not a function. Do you agree?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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#19 2017-04-04 22:05:51

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,432
Website

Re: Function and limit mcq

bobbym wrote:

But when it comes to the equation x^2 + y^2 = 4 I would say it is not a function. Do you agree?

Yes, I agree.

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#20 2017-04-04 22:29:35

iamaditya
Member
From: Planet Mars
Registered: 2016-11-15
Posts: 821

Re: Function and limit mcq

Hmm, now I understand.


Practice makes a man perfect.
There is no substitute to hard work
All of us do not have equal talents but everybody has equal oppurtunities to build their talents.-APJ Abdul Kalam

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#21 2017-04-05 00:51:37

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 746

Re: Function and limit mcq

Hmm, you need to find the max. and min. value of a quadratic equation. The max value of a quadratic equation is as follows:
a>0-∞
a<0--D/4a
a>1-∞
a>2-∞

What is this how you do this???

And question 1 ans is it is not a function!!!!!!


Malik

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#22 2017-04-05 01:37:11

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 746

Re: Function and limit mcq

Now Any one also explain about why eq of circle is not a function


Malik

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#23 2017-04-05 02:04:32

zetafunc
Moderator
Registered: 2014-05-21
Posts: 2,432
Website

Re: Function and limit mcq

Did you see post #14?

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#24 2017-04-05 02:44:07

Zeeshan 01
Member
Registered: 2016-07-22
Posts: 746

Re: Function and limit mcq

You can clearly see that that isn't the case here: look at where gets mapped to, for instance.

PLease Explain this liNE????


Malik

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#25 2017-04-05 02:47:11

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Function and limit mcq

Please point out the post where that comes from.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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