maths revision - gcse and additional notes

29
Contents 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 )

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  • 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
    • Differentiation
    • Integrals
    • Finding the constant
    • Stationary points
    • Motion with Variable Acceleration
  • Binomial
    • Distribution
    • Expansion
  • The Discriminate
    • What is the Discriminate
    • Using the Discriminate
    • 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
    • For example:
      • y=sin2x becomes y=sinx
  • When stretching/compressing a line along the y-axis, the stretch is to the number given
    • For example
      • y=3sinx becomes y=3sinx
  • For example:
    • Curve y=x translated to give y=f(x)
  • Move right first f(x-2)
    • 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:
    • 3 sides are the same (SSS)
    • 2sides + included angle are the same (SAS)
    • 2angles + 1side are the same (ASA or AAS)
    • 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)
    • 2a) x+4x-5 first draw graph in book
    • To solve the equation make a grid
          • =0 therefore y=0 when x=-5 and 1
  • 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:
    • Take the co-efficient of x at be, for example in:
    • abc
      • x + 6x + 1
    • Half this and then square it. Both add and subtract it from the equation (so the equation doesnt change) like so:
      • x + 6x + (6/2) (6/2) + 1
    • This can be factorised into:
      • (x+3) + 8
    • To check you can expand to get:
      • x +6x + 9 + (-9 +1)
    • 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:
    • E.g. y=3x+4x-3x+2
  • For long equations, differentiate in parts and then add/subtract as needed
    • 1 st(3x) multiply the power by themultiple of x=15x
    • Then minus 1 from the power=15x
    • Repeat for all parts, remembering the signs:
      • = 15x+16x - 6x [+2] ...(continued)

d dx Multiple of x Power 10.

  • For a whole number i.e. The 2, it will =0
  • Therefore the answer is:
    • 15x+16x - 6x
  • Remember:
    • For things like 5x they become 5
    • x = x not x
    • x = x = 1
    • 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.
    • 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:
    • E.g. y=3x+4x-3x+2
  • Do it in parts:
    • ( 3x+4x-3x+2)
    • Take the multiple, like 3, and divide it by the power + 1
    • In this case you would get 3/6. You then take the x, x here, and add 1 to the power again, x
    • You place this over the multiple in the fraction to give you: [(3x)/6]
    • Continue like this, adding and subtracting according to the equation given
    • For a constant, like 2, simply at x, thus 2 = 2x
    • Then simplify if possible
      • The example above becomes 2x
    • 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
    • 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
    • For example:

IntegrateSubstitute 16.

  • DONT FORGET TO PUT IT INTO THE PREVIOUS EXPRESSION!
    • 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
    • For the first part:
        • because
        • So x=0 or x=2making them stationary points thus a possible expression
    • For the second part:
      • Where k is a constant which is an alternative expression
  • The curve passes through the point (3,2). Taking as , find the equation of the curve
    • Find the integral:
    • Find the constant:
    • Substitute this into the equation from the integration:
      • Or

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
    • So, or
  • Then find the 2 ndderivative
  • Substitute one possible value for x into this equation
    • So at x=2 a minimum
    • 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:
    • At x=2 is a minimum
    • At x=-1 is a maximum
  • It is important to say that the co-ordinate is a max/min/point of inflection

20.

  • Key:
    • v = velocity
    • u = initial velocity
    • a = acceleration
    • t = time
    • s = displacement
  • Equations:
    • v = u + at
    • s = [(u + v)/2] X t
    • 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:
    • Find an equation for v with the following equation
    • s = 5t - t + 3
    • ds/dt = 10t 1
    • Thus v = 10t 1
    • Find an equation for a with answer above
    • 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:
    • a = 2 6t(find v)
    • v = a dt
    • (2-6t) = 2t [(6t)/2] + c
    • v = 2t 3t + c
      • At t = 0; v = 1
    • 1 = 0 0 + c
    • c = 1
    • v = 2 3t + 1
    • s = v dt
    • (2 3t + 1 )
      • At t = 0; and s = 0
    • = [(2t)/2] [(3t)/3] + t
    • s = t - t + t + c
    • 0 = 0 0 + 0 + c
    • c = 0

22.

  • Distribution
  • Expansion
    • Pascals Triangle

23.

  • Two mutually exclusive events (meaning that if something happens, something else cannot happen)
  • If a trial is conducted n times,
    • P is the probability of success in every trial
    • q is the probability of failure
      • Note:
  • The probability of exactly r successes is:
    • Where x is number of success and r=0,1,2...

24.

  • Remember:
    • Indices of a term = the sum of indices of expression
      • For example:
  • 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
    • 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:
    • abc
    • Useto find the discriminate so it will be:
    • Then, when , you can factorise to get
      • So,
      • Or
  • 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:
    • Ascannot be any less than 0, when this is multiplied by 4 it can be no less than zero
    • Therefore -25 has o be the minimum possible answer