theory statements Flashcards
(31 cards)
proposition 2.3 (sqrt(2) is irrational)
√2 is NOT rational
de moivre’s theorem
Let z1, z2 be complex numbers with polar forms
the fundamental theorem of algebra
Every polynomial equation of degree at least 1 has a root in C
euler’s formula
For a convex polyhedron with V vertices, E edges and F faces, we have
V − E + F = 2
the fundamental theorem of arthmetic
Let a , b ∈ Z . We say a divides b (or a is a factor of b ) if b = ac for some integer c . When a divides b , we write a b . ∈
Let a , b Z . We say a divides b (or a is a factor of b ) if b = ac for some integer c . When a divides b , we write a│b
theorem 12.1 (there are infinitely many prime numbers)
n/(ln(n))
fermat’s little theorem
Let p be a prime number, and let a be an integer that is not divisible by p . Then a^ p − 1 ≡ 1 mod p
binomial and multinomial theorems
Let P be a process which consists of n stages, and suppose that for each r , the r^th stage can be carried out in a r ways. Then P can be carried out in a 1 a 2 . . . a (n) ways.
inclusion-exclusion principle
Logically enough, we call a set S a finite set if it has only a finite number of elements. If S has n elements, we write Sn. If a set is not finite, it is said to be an infinite set.
For example, if S = {1,3,2), then S is finite and S = 3. And Z is an infinite set.
real numbers are uncountable
the powerset of a set has strictly larger cardinality
│N│ = │Q│= │N x N│ and │N│ < │R│
the subgroup test
Let G be a group, and let H be a subset of G . The H is a subgroup of G if the following three conditions hold: ∈ (1) e (2) x , y (3) x ∈ ∈ H (where e is the identity element of G ), H xy H ⇒ ⇒ x − 1 ∈ H , ∈ H
lagrange’s theorem
squeeze theorem
differentiation formulae: power rule
power rule is given by, d(xn)/dx OR (xn)’ = nx^n-1, where n is a real number.
d(x^n)/dx = n.x^n-1
differentiation formulae: sum rule
If f and g are continuous at a point c , then the sum f + g is continuous at c .
differentiation formulae: constant multiple rule
d(k f(x))/dx = k d(f((x))/dx
differentiation formulae: product rule
If f and g are continuous at c , then the product function f . g (defined by ( f . g )( x ) = f ( x ) g ( x ) ) is continuous at c
differentiation formulae: quotient rule
If f and g are continuous at c , and g ( x ) = 0 for all x , then the quotient f g is continuous at c
differentiation formulae: chain rule
Dy/dx = dy/du × du/dx
rolle’s theorem
“If a function f is defined in the closed interval [a, b] in such a way that it satisfies the following condition: i) f is continuous on [a, b], ii) f is differentiable on (a, b), and iii) f (a) = f (b), then there exists at least one value of x, let us assume this value to be c, which lies between a and b i.e. (a < c < b ) in such a way that f‘(c) = 0.”
In short: uwu
1) f(x) is continuous on [a,b],
2) f(x) is differentiable on (a,b), and
3)f(a) = f(b)
then there exisits at least on c in (a,b) such that f’(c) = 0
mean value theorem
The function f(x) is continuous over the interval [a, b].
The function f(x) is differentiable over the interval (a, b).
There exists a point c in (a, b) such that f’(c) = [ f(b) - f(a) ] / (b - a)
→a and →b are orthogonal if and only if →a*→b = 0
→a x →b is orthogonal to both →a and →b