maths revision - gcse and additional notes
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TRANSCRIPT
- 1. Straight from My Revision Book By the way, this is probably repeating the other one a lot (Special thanks to Moji who is a star )
2.
- Transformations of Graphs
- Congruency
- Completing the square
- Calculus
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- Differentiation
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- Integrals
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- Finding the constant
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- Stationary points
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- Motion with Variable Acceleration
- Binomial
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- Distribution
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- Expansion
- The Discriminate
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- What is the Discriminate
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- Using the Discriminate
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- Finding Minimum or Maximum Value
3. 4.
- When we have to stretch a line along the x-axis, we have to stretch to nwhere n is the number given
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- For example:
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- y=sin2x becomes y=sinx
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- When stretching/compressing a line along the y-axis, the stretch is to the number given
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- For example
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- y=3sinx becomes y=3sinx
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- For example:
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- Curve y=x translated to give y=f(x)
- Move right first f(x-2)
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- It is -2 because x is squared in the question and moved to the right
- Move down -4
- Therefore: y=(x-2)-4
- Again it is squared because the question has x
y x 0 x A (2,-4) y=x 5.
- Similarity : when the angles are the same but thelengths are different
- Triangles are congruent if:
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- 3 sides are the same (SSS)
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- 2sides + included angle are the same (SAS)
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- 2angles + 1side are the same (ASA or AAS)
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- In a right angled triangle, the hypotenuse +1side are the same (RHS)
- You will always be given the graph and an equation
- For example (p408 ex17g)
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- 2a) x+4x-5 first draw graph in book
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- To solve the equation make a grid
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- =0 therefore y=0 when x=-5 and 1
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- Note : if this doesnt work y=0
x -6 -5 -4 -3 -2 -1 0 1 2 x 36 25 16 9 4 1 0 1 4 +4x -24 -20 -16 -12 -8 -4 0 4 8 -5 -5 -5 -5 -5 -5 -5 -5 -5 -5 y 7 0 -5 -8 -9 -8 -5 0 7 6.
- When you are told to complete the square:
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- Take the co-efficient of x at be, for example in:
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- abc
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- x + 6x + 1
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- Half this and then square it. Both add and subtract it from the equation (so the equation doesnt change) like so:
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- x + 6x + (6/2) (6/2) + 1
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- This can be factorised into:
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- (x+3) + 8
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- To check you can expand to get:
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- x +6x + 9 + (-9 +1)
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- Remember: that if it is 4x + ... it has to be factorised into 4(x + ...) rather than (4x + ...)
7. 8.
- Differentiation
- Integrals
- Finding the constant
- Stationary points
- Kinematics
9.
- To differentiate:
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- E.g. y=3x+4x-3x+2
- For long equations, differentiate in parts and then add/subtract as needed
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- 1 st(3x) multiply the power by themultiple of x=15x
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- Then minus 1 from the power=15x
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- Repeat for all parts, remembering the signs:
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- = 15x+16x - 6x [+2] ...(continued)
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d dx Multiple of x Power 10.
- For a whole number i.e. The 2, it will =0
- Therefore the answer is:
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- 15x+16x - 6x
- Remember:
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- For things like 5x they become 5
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- x = x not x
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- x = x = 1
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- x = x
- ...(continued)
11.
- The second derivative tells us if a point is a maximum point, minimum point or a possible point of inflection
- This is just differentiating what you already have differentiated
- The third derivative tells us if a point is a point of inflection if it does not equal zero. If it does equal zero it is not possible at this level.
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- It shouldnt equal zero but if it does just remember to putnot possible at this levelas there may be a mistake in the question
12.
- Integration is the inverse process of differentiation
- The symbol for this is
- To integrate:
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- E.g. y=3x+4x-3x+2
- Do it in parts:
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- ( 3x+4x-3x+2)
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- Take the multiple, like 3, and divide it by the power + 1
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- In this case you would get 3/6. You then take the x, x here, and add 1 to the power again, x
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- You place this over the multiple in the fraction to give you: [(3x)/6]
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- Continue like this, adding and subtracting according to the equation given
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- For a constant, like 2, simply at x, thus 2 = 2x
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- Then simplify if possible
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- The example above becomes 2x
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- Then add c where c is the constant
13.
- There are two formulae that need to be learnt:
- Note:Finding the original function given its derivative is the same as finding the integral
1. 2. Where a is a constant 14.
- For definite integrals, numbers are given
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- E.g.
- You must integrate as normal
- Then you take the number for the upper limit and substitute it in for x, x=3
- Do the same for the lower limit, x=1, and subtract this from the previous value. Giving:
- Note:As c vanishes when you work the previous expression, it is common to replace c altogether and write:
- It can also be found using the formula:
- This can be used to find areas of curves
Upper limit Lower limit 15.
- To find the constant, you will be given co-ordinates which then can be substituted into an expression which will be used to find the constant
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- For example:
IntegrateSubstitute 16.
- DONT FORGET TO PUT IT INTO THE PREVIOUS EXPRESSION!
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- So the answer is:
- You could lose marks for leaving it just like that!
17.
- Explain whyis a possible expression for the gradient of the curve and give an alternative expression for
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- For the first part:
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- because
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- So x=0 or x=2making them stationary points thus a possible expression
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- For the second part:
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- Where k is a constant which is an alternative expression
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- The curve passes through the point (3,2). Taking as , find the equation of the curve
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- Find the integral:
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- Find the constant:
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- Substitute this into the equation from the integration:
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- Or
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18.
- The 2 ndderivative tells us if a point is a maximum, a minimum, or a possible point of inflection
- The 3 rdderivative tells us if a point is a point of inflection if it doesnt equal zero
- If it does equal zero it is not possible at this level
- However this should only occur if there was a mistake in workings or the question
19.
- For
- Find the first derivative
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- So, or
- Then find the 2 ndderivative
- Substitute one possible value for x into this equation
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- So at x=2 a minimum
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- So at x=-1 a maximum
- You will often be asked to find the possible points (co-ordinates) where the stationary points are. To do this, simply substitute the possible values of x into the equation given
- Therefore:
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- At x=2 is a minimum
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- At x=-1 is a maximum
- It is important to say that the co-ordinate is a max/min/point of inflection
20.
- Key:
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- v = velocity
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- u = initial velocity
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- a = acceleration
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- t = time
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- s = displacement
- Equations:
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- v = u + at
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- s = [(u + v)/2] X t
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- v = u + 2as
- To find an equation for v you can do the derivative of s (ds/dt)
- To find an equation for a you can do the derivative of v (dv/dt)
- Example:
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- Find an equation for v with the following equation
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- s = 5t - t + 3
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- ds/dt = 10t 1
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- Thus v = 10t 1
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- Find an equation for a with answer above
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- dv/dt = 10 so a = 10
- Similar to doing the 2 ndderivative
21.
- v = ds/dts = v dt
- a = dv/dtv = a dt
- Area under the line which also given the velocity in a time-distance graph
- Example:
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- a = 2 6t(find v)
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- v = a dt
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- (2-6t) = 2t [(6t)/2] + c
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- v = 2t 3t + c
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- At t = 0; v = 1
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- 1 = 0 0 + c
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- c = 1
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- v = 2 3t + 1
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- s = v dt
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- (2 3t + 1 )
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- At t = 0; and s = 0
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- = [(2t)/2] [(3t)/3] + t
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- s = t - t + t + c
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- 0 = 0 0 + 0 + c
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- c = 0
22.
- Distribution
- Expansion
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- Pascals Triangle
23.
- Two mutually exclusive events (meaning that if something happens, something else cannot happen)
- If a trial is conducted n times,
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- P is the probability of success in every trial
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- q is the probability of failure
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- Note:
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- The probability of exactly r successes is:
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- Where x is number of success and r=0,1,2...
24.
- Remember:
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- Indices of a term = the sum of indices of expression
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- For example:
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- However, Pascals Triangle is long to use so thebutton on the calculator is used instead
- So, if we want to work out the co-efficient ofin the expression, we need
- Another way is:
- In general this is:
- Remember:
- Using the co-efficients of each expansion we can get Pascals Triangle
- Its easy to work out as you just add the previous numbers
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- For example: 1211331
- The triangle is symmetrical and always has 1 at the beginning and end of each line
Power of binomial Power of x and 25. 26.
- What is the Discriminate
- Using the Discriminate
- Finding Minimum or Maximum Value
27.
- Key: = discriminate
- When using the equation the decides the answer you get
- If, you get anon-realnumber as it is a minus
- If , you gettworeal distinctanswers
- If, you getone real equalanswer
- It is important to know the correct terminology here
28.
- For example:
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- abc
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- Useto find the discriminate so it will be:
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- Then, when , you can factorise to get
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- So,
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- Or
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- Whenorthe answers are above the x-axis therefore the answer is:
29.
- If given an equation where the constant is negative to find the minimum, the only possible answer is for the equation to equal zero
- For example:
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- Ascannot be any less than 0, when this is multiplied by 4 it can be no less than zero
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- Therefore -25 has o be the minimum possible answer