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#26 2017-04-05 18:31:47

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

Re: Function and limit mcq

Post #14


Malik

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#27 2017-04-05 19:17:46

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

Re: Function and limit mcq

Okay, what do you not understand?


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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#28 2017-04-06 01:51:03

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

Re: Function and limit mcq

I want to say eq of circle why not implicit function..


Malik

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#29 2017-04-06 02:05:11

Bob
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Registered: 2010-06-20
Posts: 10,052

Re: Function and limit mcq

Zetafunc's formal definition and the vertical line test both come down to a simple test:  for any x is there a unique y?  For the circle most x values give two values of y so not a function.

I need to look again at your quadratic.  At first sight it doesn't make sense to me.  back shortly.

later edit:  If a quadratic has a positive x^2 term then it is U shaped and therefore has a finite minimum.  As x tends to + or - infinity y will tend to infinity so there is no finite maximum.

If, however,  the x^2 term is negative, then it is upsidedown U shaped so it has a single finite maximum.

I recommend you try out some possible quadratics using the function grapher.  While there try y =  √ (4 - x^2).  you see you only get half a circle.

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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#30 2017-04-06 23:45:05

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

Re: Function and limit mcq

Zeeshan 01 wrote:

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!!!!!!



Sorry for the late reply but you may visit this site:https://brilliant.org/wiki/maximum-valu … -equation/


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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#31 2017-04-07 02:48:37

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

Re: Function and limit mcq

It is saying that max value is -b÷a
Is it CORRECT? ?


Malik

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#32 2017-04-07 19:51:36

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

Re: Function and limit mcq

You can jot the value of -b/a instead of x in ax²+bx+c and can see it yourself.


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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#33 2017-04-07 20:34:09

zetafunc
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Registered: 2014-05-21
Posts: 2,432
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Re: Function and limit mcq

Your maximum would have to either be a stationary point or infinite. Have you tried differentiating your quadratic?

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#34 2017-04-07 21:12:50

Bob
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Registered: 2010-06-20
Posts: 10,052

Re: Function and limit mcq

hi Zeeshan 01

It is possible to show that all quadratics have a line of symmetry, and that for ones of the form y = ax^2 + bx + c this will be a verttical line.

If we start with the quadratic formula for the two roots:

it should be obvious that the two roots are symmetrically placed either side of the line

so the maximum will not be at

as you ask in post 31

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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#35 2017-04-08 02:41:17

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

Re: Function and limit mcq

I know quadratic formula but what is line of symmetry? ?


Malik

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#36 2017-04-08 06:41:22

Bob
Administrator
Registered: 2010-06-20
Posts: 10,052

Re: Function and limit mcq

Another name would be a mirror line.

puUXx7J.gif

http://www.mathsisfun.com/geometry/symm … hapes.html

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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#37 2017-04-08 16:17:39

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

Re: Function and limit mcq

Hmm thx!!


Malik

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#38 2017-04-09 00:30:56

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

Re: Function and limit mcq

bob bundy wrote:

hi Zeeshan 01

It is possible to show that all quadratics have a line of symmetry, and that for ones of the form y = ax^2 + bx + c this will be a verttical line.

If we start with the quadratic formula for the two roots:

it should be obvious that the two roots are symmetrically placed either side of the line

so the maximum will not be at

as you ask in post 31

Bob


Hmmm, but as far as I know, the max and min value of a quadratic polynomial is when the value of x is

. Check the link above.


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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#39 2017-04-09 07:24:14

Bob
Administrator
Registered: 2010-06-20
Posts: 10,052

Re: Function and limit mcq

I agree.  That's what I said.

Bob


Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob smile

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