Week 1 Flashcards
And all jump
All discontinuities are?
Criteria for continuity of a function at a point given by limits of sequences
Definition From functions and sequences of convergence
If atleast one of the left or right limit is Infinite
However you define f(x_0) , f will not be continuous
f is continuous at x_0 if? Definition from limits
Of a function at a point
As x->0
A set A € R is said to be bounded above if
For A€ (-inf, M] for some M€R
A set A € R is said to be bounded below if
A€ [m, infinity) for some m€R
If x is real, Neighbourhood of x is
Any open interval (a,b) such that x€(a,b)
ε neighbourhood of x?
For ε>0 , (x-ε, x+ε)
x is called an interior point of A if
A contains a neighbourhood of x
A set B is closed if
It’s complement is open
Axiom of completeness
Every set that is bounded above has a supremum, every set that is bounded below has an infimum
Define supremum? How to prove that M is supremum
Least upper bound
Prove that it’s an upper bound
Prove there is no M’ that is an upper bound but less than M
Define infimum? How to prove that m is infimum?
Greatest lower bound
Prove that it’s a lower bound
Prove there is no m’ that is a lower bound but greater than m
Definition of a countable set A on Real line
If it is either finite or there exists a bijection between A and N
Which sets are countable, which aren’t
Z , Q are countable
R isnt
A sequence is said to be a Cauchy sequence if?
Cauchy’s criterion
A sequence converges if and only if it’s a Cauchy sequence
Bolzano Weierstrass
Define all of the below
The set Δ is called the DOMAIN OF DEFINITION of the function
The set of all of the values when x runs over Δ , f(x) is said to be the RANGE of f, denoted ran(f)
Reimann Zeta function
Which converges for s>1
Natural domain, define
If f(x) is given by an explicit formula, natural domain is set of values x€R such that the formula makes sense
Natural domain of below?
Define
A periodic function
An odd function
An even function
A function is said to be bounded if ?
Unbounded if?
Define punctured neighbourhood
That 0 should be x_0
f(x) converges to y_0 as x->x_0 if
Write convergence in terms of neighbourhoods
For f defined on (a,infinity) a€R, limit of f(x) as x-> infinity is given?
For f defined on (a,infinity) a€R, limit of f(x) as x-> infinity is given?
(In terms of neighbourhoods)
Dirichlet function
Characteristic function of set A