# Mathematics: Post your doubts here!

#### destined007

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Do question 4.

#### 1357913579

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so only number 4 no need to do 1 2 3 5 6 7 8 9 and 10 thankss
just write yes if this is the case.

#### 1357913579

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and for drawing its graph in number 4 we just have to put the values of x lets say -4,-3,-2,-1,0,1,2,3,4 for instance put in the f(x) equation get the value of y and plot the graph is it like that thanks if not please solve if you can respont urgently please as you now i have very short time.

#### destined007

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yes, exactly.

#### 1357913579

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THIS IS THE QUESTION FIND THE MAXIMUM AND THE MINMUM POINTS
F(X)=3X^4+1

#### XPFMember

XPRS Moderator
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Assalamoalaikum!!

Well ...check my notes..differentiation..it's included in there..
In short, u have to differtiate the equation.... then put dy/dx = 0
you'll get the x coordinates put in the main eqn to get the value of...find d^2 y / dx^2 to find the nature...u can find more detail in my notes...as far as i remember i have this one added...try doing it yourself..it'll build your confidence too..when u understand and do and then get it correct... if u need help...dont hesitate though

#### 1357913579

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I HAVE SOLVED MANY PROBLEM LIKE THESE BUT THE PROBLEM IS THAT FOR D^2Y/DX^2=0 WHEN WE PUT THE VALUE OF X SO IS IT MAXIMUM OR MINIMUM OR POINT OF INFLECTION HAS A VERY SPECIAL CASE.

#### XPFMember

XPRS Moderator
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hold on cud u put the question again... 3x^4+1

power is 4 right?

#### destined007

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1357913579 said:
THIS IS THE QUESTION FIND THE MAXIMUM AND THE MINMUM POINTS
F(X)=3X^4+1

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#### XPFMember

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Assalamoalaikum..destined007
do this type of questions come in the exam?? I never came across any such question in the pastpaper?!

thanx anyways..i never thought of this jazakAllah Khairen!

#### destined007

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yeah. This can come in exam.

#### XPFMember

XPRS Moderator
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hmm i never saw it though...but gud i know now...

#### 1357913579

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THEN WHAT ABOUT THE PROBLEM F(X)=2X^3-12X^2+24X+6 EVEN IN THIS ONE WE GET F DOUBLE DASH(X) =0 THEN WHEN WE TAKE X=-1 AND X=1 SO WE GET BOTH NEGATIVE VALUES PLEASE EXPLAIN

#### 1357913579

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AND SO THE ANSWER FOR THE ONE YOU POSTED IS MINIMUM AS D^2Y/DX^2 CHANGES FROM NEGATIVE TO POSITIVE MEANING MAXIMA TO MINIMUM AND THE VALUES WOULD BE (0,1)

#### destined007

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1357913579 said:
THEN WHAT ABOUT THE PROBLEM F(X)=2X^3-12X^2+24X+6 EVEN IN THIS ONE WE GET F DOUBLE DASH(X) =0 THEN WHEN WE TAKE X=-1 AND X=1 SO WE GET BOTH NEGATIVE VALUES PLEASE EXPLAIN

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#### 1357913579

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BY THE WAY IS INFLEXION IN THE P1 SYLLABUS THANKS VERY VERY MUCH FOR ANSWERING

#### destined007

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I dont think so. However, do look at some of its questions. You never now what CIE will give in the exam.

#### VelaneDeBeaute

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This was a question i encountered in our Co-ordinate geometry class . I found the co-ordinates of one vertex but equating the equations by there's no way except the graph work i think this can be solved !! It might seem easy to you guys but its given me a hell already !! :x

The equations of two sides of a square are y = 3x - 1 and x + 3y -6 = 0. If ( 0, -1) is one vertex of the square find the coordinates of the other vertices.

:: Core Maths 3rd Edition; Pg 91, Q 11.

Answers = ( 9/10 , 17/10 ) <-- Found it !!
Other two can be
Either ( -18/10 , 26/10 ) and ( -27/10 , -19/10 )
Or ( 36/10 , 8/10 ) and ( 27/10, -19/10) !!

#### 1357913579

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