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Author Topic: Compilation of Tricky Points + Nifty Stuff  (Read 6975 times)  Share 

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kyzoo

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Compilation of Tricky Points + Nifty Stuff
« on: November 03, 2010, 03:31:40 pm »
+9
Just doing the same thing as I did for Methods =X

http://vcenotes.com/forum/index.php/topic,20778.0.html

EXAM TECHNIQUE

●  For Exam 2, ALWAYS ALWAYS ALWAYS USE THE CALCULATOR IF YOU CAN. Try to never do stuff by hand even if you; even simple stuff like “3+2”

●  Always use the maximum possible amount of working out steps you can. DON'T SKIP STEPS, NEVER DO MENTAL ARITHMETIC.

●  Always draw diagrams first before you start solving the question
E.g. for tank inflow outflow problem, always convert the information into a diagram before you start answering the questions

●  Always draw large diagrams

GENERAL

●  When the question asks for 1/2/3/4 decimal places, and the last decimal place is a 0, you have to include that 0 anyway. For example 2.1 to two decimal places is 2.10, not 2.1.

●  Distinguish between when it is asking for a certain number of decimal places, or an exact solution. With decimal places you can just use the calculator. If it doesn't ask for decimal places, assume it is asking for exact solution

● 
=>

~ Whenever there is an even denominator present when "powering" the equation, the sign is necessary

●  Put all your solutions into the last line for clarity

●  Line up your "= signs" to make it easier for examiners to read your solution

●  For proof question, always state what you have proven at the end

●  Always simplify answers at the end. Always rationalize any surds.

●  Do not confuse SIGNIFICANT FIGURES with DECIMAL PALCES




●  Always check to see if the domain is restricted when they give you a function

DRAWING GRAPHS

●  Always label curves with its corresponding equation ...

●  Whenever you have to sketch a weird function that you are unsure about, always get the calculator graph first then sketch. Especially do this when you have to draw two functions on the same set of axis. Otherwise you may get the shapes wrong.

●  When drawing a curve approaching an asymptote, make sure the curve never touches or bends away from the asymptote whilst approaching.

●  Do not assume the domain to always magically be the maximal domain. You must interpret the situation and restrict the domain accordingly.

●  Whenever part of the graph you need to curve overlaps with a line that is already there, you must clearly indicate this (probably best by using some colour other than black).

~ From Derrick Ha book: If you need to draw an or asymptote, draw them directly beside the axis, rather than on

●  When drawing graph lines, put arrows on the end of the lines to indicate that they continue on

●  With any hybrid function or functions with a restricted domain, you need to take care to indicate endpoints and whether they are open or closed

●  Dr. He: A dotted line alone is not an asymptote. You need to indicate that it is an asymptote with the label

●  Always label axis-intercepts with co-ordinates rather than a single number. Label y-intercept as and x-intercept as

●  For reciprocal functions, watch out for the horizontal asymptote. Really easy to miss.

METHODS THEORY

FUNCTIONS

●  In an inequation, when you reciprocal the whole thing you must reverse the signs





● 
VCAA 2010 Spesh Exam 2 Question 4 c.)

●  has 3 real solutions . But 2 distinct real solutions

●  is the inverse function.

LOGARITHMS

●  , because c can be any number.

● 


or alternatively





ELLIPSE AND HYPERBOLAS

●  Major axis of an ellipse is the DIAMETER, not the radius. The semi-major axis is the radius

TRIGNOMETRY

●  Derivatives and antiderivatives for sinusoidal functions only work if they are in radians measurements. Thus if it is in degrees, you must convert to radians.




●  is not equivalent to . The former is a relation, the latter is a function. Thus the range of

●  Make a habit of explicitly stating the restricted domain of inverse sinusoidal functions

VECTORS

●  The zero vector is Not

●  Dr He: It is wrong to say that or That is geometry notation, not vector notation

●  Dot product of and is S NOT or even Not having the dot is a big mistake

●  The angle between two vectors is when they are placed tail-to-tail or head-to-head

●  You cannot square a vector. is invalid notation

COMPLEX NUMBERS

●  VCAA 2010 Exam 1 Question 1: Differentiate between roots/solutions and factors of a polynomial equations

●  Must differentiate between and ; complex region of is the entire Argand diagram except for the origin

●  Always label complex regions

●  For The origin is always an open endpoint.

DIFFERENTIATION

●  Be careful when it asks for “rate of decrease”, if the derivative is a negative value than the "rate of decrease" has a positive value

●  Be careful about whether it is asking for the normal or the tangent

●  When stuff is leaking out that is a negative rate of change

●  You are in trouble if This can be any type of stationary point and you need to use a gradient sign test to ascertain it. Do not automatically assume that it is an inflection point. Example:

●  Gradient sign test (Derrick Ha)
Need to give actual values of gradient immediately to left and to the right of the point, rather saying they are >0 and <0




\ _ /
Local minimum at (0,3)

●  In implicit differentiation where you have a relation like , BE VERY CAREFUL TO DIFFERENTIATE THE “8” TO BECOME “0”

●  Although follows fraction laws
(  is not a fraction), does not obey fraction laws.
    
●  Difference between and
is always a function of x.

is not necessarily a function, it is just the gradient of the tangent at a point.



● 

ANTI-DIFFERENTIATION

●  When anti-differentiating an indefinite integral, take care to include the “+ c” part.

●  Derivative does not exist at cusp points or where function is not continuous

●  , unless the domain specified otherwise
NB: 2010 Exam 1 Question 7 DID have the domain specified. So you had to shed the modulus and replace them with brackets. You must replace modulus with brackets when the domain is specified

●  . You must have the expression enclosed within a bracket. is two expressions where is an undefined expression

●  Remember to change limits for substitution method

●  Dr He: For substitution, do not change the limits until the integration variable is du













AREA UNDER THE GRAPH

●  Always draw the graph first before finding the area under the curve

●  Avoid integration across asymptotes

●  For solid of revolution, by careful to put in front of the integral term when finding the volume of a solid of revolution.

●  Solids of revolution
~ Be careful you rotate around the right axis
~ Area you rotate must be adjacent to the axis

DIFERENTIAL EQUATIONS

●  Make sure you have an appropriate number of arbitrary constants

●  The slope field curve does not equal

VECTOR FUNCTIONS

●  The domain of the Cartesian equation WILL ALMOST ALWAYS be restricted. Sketch and graphs in order to ascertain the domain and range of the Cartesian equation

●  Put whenever antidifferentiate vector functions

●  When sketching the path of a particle you have to
~ Indicate initial position at 
~ Indicate direction
~ Indicate restricted domain/range and Cartesian equation

●  If they give you and do not exist as the graphs of is not differentiable at

●  Terminal velocity = asymptote velocity, not maximum velocity

DYNAMICS

●  Equation motion is
e.g. -

●  Reaction force DOES NOT EQUAL Normal force. Normal force is a part of the reaction force. Reaction force can act at any angle to the slope

●  F does not equal unless it is on the brink of moving or it is moving

●  Constant velocity means

●  Remember that weight force is , not

●  Easy to forget component of weight force down the slope especially when there is a force towing the object up the slope.

●  When the question states a “push”, this is almost never included as a force in the force diagram, as the force acts for only a moment.
VCAA 2007 Exam 2 Q20

●  Always use force diagram in working out for dynamics question

●  CONVEYOR BELT QUESTIONS EXPLAINED
~ Friction used to pull object. So in this special case, friction is in the direction of motion.

~ can have a value bigger than 1

~ Belt can accelerate faster than object on belt. When this happens the object slips down the belt because of its negative relative acceleration, yet it still has a positive acceleration relative to the ground.

~ Object has maximum acceleration determined by coefficient of friction of belt. Cannot exceed this acceleration, and if belt exceed this, object still remain at maximum acceleration



« Last Edit: November 13, 2010, 12:56:49 am by kyzoo »
2009
~ Methods (Non-CAS) [48 --> 49.4]

2010
~ Spesh [50 --> 51.6]
~ Physics [50 --> 50]
~ Chem [43 --> 46.5]
~ English [46 --> 46.2]
~ UMEP Maths [5.0]

2010 ATAR: 99.90
Aggregate 206.8

NOTE: PLEASE CONTACT ME ON EMAIL - [email protected] if you are looking for a swift reply.

kyzoo

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #1 on: November 03, 2010, 03:33:13 pm »
+2
GENERAL

●  Unlike in Methods, speed is essential in Spesh. Keep asking yourself – what is the fastest method I can use?

●  When stuck recite a list of concepts

RANDOM GEOMETRY

●  If for a triangle, than angle C is bigger than


METHODS THEORY

●  To find the maximal domain for a question with many parts to it, find the implied domain of each part, then find the union of each part.

(VCAA 2006 Sample Exam 2)

Consider the function f with rule

State the largest domain for which f is defined.

Easy way to do this. Take all the individuals functions of x, figure out the maximal domain for each, then find the intersection of each maximal domain. That’s how you do these types of questions.

For , the maximal domain is
For , maximal domain is
For maximal domain is

Hence the maximal domain for the entire function is

ELLIPSES AND HYPERBOLAS

●  

Prove this by using Pythagoras theorem and ellipse loci along x-axis

●  The asymptotes to the hyperbola are the solutions to  

●  Area of ellipse = .
Not in syllabus, can only be used to check answer

●  
--> circle
a same sign as b --> ellipse
a different sign from b --> hyperbola


TRIGNOMETRY

●  Inverse Circular Function Properties








VECTORS

●  You can multiply both sides of an equation by a dot product

is equivalent to




●  For  




This set of vectors is linearly dependent if determinant of following matrix = 0


●  Often easier to use geometrical methods than vector algebra methods

●  If , this is the acute angle between two vectors. If , this is the obtuse angle between two vectors


COMPLEX NUMBERS

●  In , get rid of the – sign by converting into

●   is an ellipse

●  
Specifies circle with radius “r” and centre “w”

●   is a circle

●  Solving Complex Equations Methods

~ Equating real and imaginary components
~ Completing the square/Quadratic formula
~ Factorising (Includes “fake” factorising with made-up constants)
~ De Moivre’s Theorem
~ Factor Theorem Substitution
~ Difference of two squares
~ +0
~ Conjugate Factor Theorem


●  Complex Conjugate Formulas
~
~
~(z + a + bi)(z + a – bi) = ((z+a)2 + b2))

DIFFERENTIATION

●  Some derivatives
~
~
~
~

INTEGRATION

●  When you have to find the area adjacent to the y-axis rather than the x-axis, swap the x- and y- axis, then sketch the inverse function. This makes it easier to see the required integral term

●  Integration by parts
Extension of product rule


Let u and v be functions of x

uv'=(uv)'–u'v


●  Some antiderivatives

~
~
~
~


●  Antiderivative Properties
~
~ If odd function, then
~ If even function, then
~ : prove this with change of variable method


DIFFERENTIAL EQUATIONS

●  Easier way to ensure your dashes in slope fields have correct slope
Say you have a dash at (2, 0) that has gradient 2. This should also pass through the point (3, 2). So use ruler to connect (2, 0) and (3, 2)

VECTOR FUNCTIONS

●  Distance travelled from to is found by evaluating
Distance = Speed x Time = Area under Speed-Time graph

●  Two ways to find intersection of two particle’s paths
~ Simultaneous equation between two Cartesian equations
~ Use and for the two vector equations, then equate coefficients of unit vectors
DYNAMICS

●  When there are two connected objects on different planes, there is only one force in the direction of motion. Every other force is against the direction of motion

CALCULATOR

●  Always change the domain/range for each graph, and zoom in as well. It's so easy to lose marks from not noticing features that you can't observe from afar

●  For partial fractions, use
and

●  Inputting into calculator


●  Using calculator for partial fractions
To go from single fraction to partial fraction form, use Expand
To go from partial fraction to single fraction, use comDenom

« Last Edit: November 13, 2010, 01:45:15 am by kyzoo »
2009
~ Methods (Non-CAS) [48 --> 49.4]

2010
~ Spesh [50 --> 51.6]
~ Physics [50 --> 50]
~ Chem [43 --> 46.5]
~ English [46 --> 46.2]
~ UMEP Maths [5.0]

2010 ATAR: 99.90
Aggregate 206.8

NOTE: PLEASE CONTACT ME ON EMAIL - [email protected] if you are looking for a swift reply.

taiga

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #2 on: November 03, 2010, 04:58:51 pm »
0
Cheers this should help me for my spesh exam
vce: english, methods, spesh, chemistry, physics, geography.

ex admin/mod/partner

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EvangelionZeta

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #3 on: November 03, 2010, 05:23:24 pm »
0
This deserves a sticky.
---

Finished VCE in 2010 and now teaching professionally. For any inquiries, email me at [email protected].

TrueTears

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #4 on: November 03, 2010, 05:24:37 pm »
0
kyzoo's tips just gets better and better, this is great man!

(btw there's a few latex errors you might wanna fix up :D)
PhD @ MIT (Economics).

Interested in asset pricing, econometrics, and social choice theory.

3Xamz

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #5 on: November 03, 2010, 11:42:08 pm »
0
If only you had posted this before our exams kyzoo :(

haha, but nevertheless a invaluable source of information those doing Specialist in the coming years! :)
Nice work, + Karma for you my friend :)

darkphoenix

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #6 on: November 12, 2010, 09:19:29 pm »
0
What a legend.
2009: Accounting
2010: English | Methods (CAS) | Specialist Maths | Chemistry | Chinese SL
2011: Bachelor of Commerce/Engineering @ Monash

kyzoo

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #7 on: November 13, 2010, 12:00:32 am »
0
0.o ewwww so many latex errors

X.x sorry guys i've had images off for my internet browser recently since my internet is capped, so i couldn't see all these yucky errors
« Last Edit: November 13, 2010, 01:02:57 am by kyzoo »
2009
~ Methods (Non-CAS) [48 --> 49.4]

2010
~ Spesh [50 --> 51.6]
~ Physics [50 --> 50]
~ Chem [43 --> 46.5]
~ English [46 --> 46.2]
~ UMEP Maths [5.0]

2010 ATAR: 99.90
Aggregate 206.8

NOTE: PLEASE CONTACT ME ON EMAIL - [email protected] if you are looking for a swift reply.

paulsterio

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #8 on: September 03, 2011, 10:57:30 pm »
0
the latex doesn't work properly sometimes?

TrueTears

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #9 on: September 06, 2011, 06:24:28 pm »
0
its the old typeset, the new one that this forum has is screwed up and nonconventional
PhD @ MIT (Economics).

Interested in asset pricing, econometrics, and social choice theory.

Hutchoo

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #10 on: September 06, 2011, 06:25:48 pm »
0
Ruined my tutors beautiful notes :'( Lol, this new latex is hideous.

pi

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #11 on: September 06, 2011, 08:35:00 pm »
+1
The LaTeX is better than the google one... tbh, I can't tell the difference between the look of the current one and the old VN one, but maybe its just me :o

Hutchoo, nice dp! I remember that guy walking around and gate-crashing our intense four-square game that morning. He doesn't look like snoopy though, just a VISY advert. :D

Mao

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #12 on: September 08, 2011, 10:28:26 pm »
+1
The LaTeX is better than the google one... tbh, I can't tell the difference between the look of the current one and the old VN one, but maybe its just me :o

The google API is never meant for manual use, it's more meant for script plug in. It doesn't work that well, but it's better than most.

The current renderer uses the same font, but cannot handle line-break in multiline environments ( \\ produces a line break as well as printing <br />).
« Last Edit: September 08, 2011, 10:36:05 pm by Mao »
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n0bOdY

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #13 on: September 17, 2011, 01:56:18 pm »
0
antidiff of 1/ax dx should equal 1/a * antidiff of 1/x dx which equals 1/a ln(x) + c.

Natters

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Re: Compilation of Tricky Points + Nifty Stuff
« Reply #14 on: October 11, 2011, 09:07:01 pm »
0
epic. awesome. thanks.