Real Analysis Flashcards

18
Triangle Inequality Definition of Convergence of Sequences Bolzano – Weierstrass Theorem Cauchy Sequences Contractive Sequences Order Hierarchy Surjection Injection

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Flashcards of mathematical theorems and formulae associated with real analysis and calculus concepts.

Transcript of Real Analysis Flashcards

  • Triangle Inequality Definition of Convergence of

    Sequences

    Bolzano Weierstrass Theorem Cauchy Sequences

    Contractive Sequences Order Hierarchy

    Surjection Injection

  • The sequence converges to L as if, given any > 0, there exists N such that

    < >

    If there is no such number the series diverges.

    + +

    The sequence is called a Cauchy sequence if, given any >0, there exists N such that

    < , >

    A sequence converges iff it is a Cauchy sequence.

    Every bounded real sequence contains a convergent subsequence.

    1 log !

    , > 1, > 0

    A sequence is contractive if

    +2 +1 < +1

    where is a positive constant strictly less than 1. Such sequences converge.

    If every element of B which is the image of something in the set A is the image of precisely one element of A.

    If every element of B is the image of something in the set A. The range equals the codomain.

  • Definition of Convergence of Functions at a point

    = ?

    =

    = ?

    =

    = ?

    +

    = ?

    Continuity Uniform Convergence of Functions

    Intermediate Value Theorem Differentiability

    Rolles Theorem Mean Value Theorem

  • lim

    1 = 1

    lim0

    sin

    = lim

    0

    tan

    = 1

    lim0

    log1

    = lim

    log

    = 0

    lim

    1 +

    =

    We say that as if, given any > 0, there exists > 0such that

    () <

    whenever 0 < < .

    is said to converge uniformly on an interval to a continuous function () if, given any > 0 there exists such that

    () () <

    whenever > and .

    A function () is continuous at = if () () as .

    A function is differentiable at the point = if

    () = () + ( ) +

    where L is independent of x and

    /( ) 0 as

    If is continuous on the closed finite interval [, ], then for every real number between () and (), there exists at least one point [, ] for which () = .

    If is continuous on the closed interval [, ] and differentiable on the open interval (, ), then there exists at least one point (, )such that

    = ()( )

    If a function is defined on [, ], continuous on [, ], is differentiable on (, ), and () =(), then there exists (, )such that = 0.

  • LHpitalsRule Taylor Polynomial

    Lagranges Remaindersin(y)

    cos(y)

    sinh(y), cosh(y)and their derivatives

    Other usefulHyperbolic Function Identities

    arctanh(t)and its derivative

  • If () has at least n derivatives at = , the th order Taylor polynomial for () about = is

    =0

    ()( )

    !

    If and are differentiable in an open interval containing , () = () = 0, & () 0 in except possibly at = , then

    lim

    ()

    ()= lim

    ()

    ()

    if the limit on the right exists.

    sin =1

    2

    cos =1

    2 +

    = +1 ()( )+1

    + 1 !

    cosh2 sinh2 = 1

    sech2 = 1 tanh2

    tanh = 1 tanh2

    sinh(2) = 2 sinh cosh

    cosh 2 = cosh2 + sinh2

    sinh =1

    2

    cosh =1

    2 +

    They are derivativesof each other.

    arctanh =1

    2log

    1 +

    1

    arctanh =

    1

    1 2

    arcsinh =

    1

    2 + 1

    arccosh =

    1

    2 1

  • Riemann IntegrabilityConditions

    Riemann Sum

    Fundamental Theorem of Calculus LiebnizsRule

    Odd & Even Functions Integration by Parts

    Ordinary Differential Equationsof order

    Separable ODEs

  • =1

    where are the boundaries of the subintervals, = 1 and , 1 . Labelled regular if all subintervals are equal length.

    is Riemann integrable if upper bound of lower sums and lower bound of upper sums are equal. If:

    a. continuous on [, ]

    b. monotonic on [, ]

    c. bounded on [, ] and removable discontinuities only

    ()

    ()

    =

    (for differentiating integrals with respect to a terminal variable)

    If () is continuous for then

    =

    is differentiable for < < , () = () has right derivative () at = and left derivative () at = .

    = () ==

    Odd:

    =

    Even:

    =

    Those of the form

    = ()

    (Mentally go through procedure for solving.)

    Those of the form

    , ,

    , ,

    = 0

  • General first-order linear ODEsand their integrating factors

    First-order ODEs of homogeneous type

    First-order ODEs of Bernoulli type Stability

    Second-order linear ODEswith constant coefficients

    Complementary Functionsof second-order linear ODEs

    with constant coefficients

    Strategies forfinding particular integrals

    of second-order linear ODEswith constant coefficients

    Comparison Testfor Improper Integrals

  • Those of the form

    =

    (Mentally go through procedure for solving.)

    Those of the form

    + =

    with = exp () .

    (Mentally go through procedure for solving.)

    An equilibrium solution = of an ODE is stable if, given >0 > 0 such that for every othersolution () with 0 < , < (0,).

    Asymptotically stable if

    Those of the form

    + =

    (Mentally go through procedure for solving.)

    Solve characteristic equation.

    If 2 solutions: 1 + 2

    If 1 solution: ( + )1

    (Go through complex root case mentally.)

    Ones of the form

    2

    2+

    + =

    (Mentally go through procedure for solving.)

    If () is Riemann integrable on all finite subintervals of [,), 0 () () for , and the

    improper integral ()

    exists, then () exists and

    0 ()

    () .

    Split up using superposition ideas.

    Strategic guessing (go over strategies mentally).

  • Limit Comparison Testfor Improper Integrals

    The Gamma Function

    Absolute Convergencefor improper integrals and series

    Mean of aProbability Density Function

    Fourier Transform The Harmonic Series

    The Divergence Test(a.k.a. The Dont waste my time Test)

    The Geometric Series(and its sum to infinity)

  • = 0

    1

    ! = + 1 = 0

    If () is Riemann integrable on all finite subintervals of [,); () >0 for ; ()~() as and the improper integral

    () exists, then

    ()

    exists.

    =

    ()

    where () is the Probability Density Function.

    If is Riemann integrable in all

    finite intervals and

    () 0 1, and ()

    decays monotonically to zero as

    , then =1 () converges

    iff 1() < .

    If > 0 and > 0 for all and ~ as then

    either =1 and =1

    both converge;

    or =1 and =1

    both diverge.

    If > 0 and > 0 for all and = () as then

    =1 converges =1

    converges;

    =1 diverges =1

    diverges.

    =1

    1

    Converges iff > 1.

    If 0 and decays monotonically to zero as then the alternating series =0 (1) converges.

    If > 0 for all , then

    lim

    +1

    < 1 =1

    converges;

    lim

    +1

    > 1 =1

    diverges.

  • Multiplication of Series Power Series

    Uniform Convergence of Series The Weierstrass M Test

    The Taylor Series Pochhammers Symbol

    Theorem on theConvergence of Power Series

    Addition of Power Series

  • Those of the form:

    =0

    0

    centred on 0, being independent of .

    If the series = = and =

    = are both absolutely

    convergent, then their product is given by the absolutely convergent series

    = =

    =

    If () for all , where is independent of and =0 converges, then

    =0 () converges uniformly on

    the interval .

    This sum is a continuous function if () is continuous.

    If the series =0 () converges

    for all where is an open or closed interval, we say that it converges uniformly on if the sequence of partial sums = =0 () converges uniformly on

    .

    Defined for {0} by

    ()

    = 1, = 0

    + 1 + 1 ,

    =0

    ()

    !

    The special case = 0 is sometimes called the Maclaurinseries.

    If the power series =0

    and =0

    have radii of convergence and respectively, then =0

    (+)

    converges at least for