II] Numbers and arithmetics Flashcards
What is the sign for “positive integers”?
IN
What is the set of “positive integers”?
IN = {0, 1, 2, 3 … }
What is the symbol for “set of integers”?
Z
What is the set of “integers”?
Z = {…, -3, -2, -1, 0, 1, 2, 3, …}
What is the symbol for the “set or rationals”?
ℚ
What is the set of “rationals”?
ℚ = {x⎥∃ p, q ∈Z, x=p/q
What is the symbol for the “set or reals”?
ℝ
What is the set of “reals”?
ℝ = {all the numbers}
What is “transitivity of equalities”?
(a=b, b=c) => a=c
What is “closure property” and which operations does it concern?
Addition and product
∀x, y ∈ℝ, x+y ∈ℝ, x×y ∈ℝ
To which operations does “commutativity” apply?
Addition and product in ℝ
To which operations does “associative property” apply? And what is it?
Addition and product
a+(b+c) = (a+b)+c
What are the “neutral elements” for addition and product?
+ : 0
× : 1
How do you determine the “neutral element” for an operation?
y is the inverse of x for ✻
x✻y = neutral element for ✻
What is a subtraction?
∀a, b ∈ℝ
a-b = a+(-b)
What is a division?
∀a, b ∈ℝ
a/b = a×b⁻¹
What is “distributive property”?
∀a, b, c ∈ℝ a(b+c) = ab+ac
How to simplify a fraction?
a/b = a/b × c/c = ac/bc
What is an exponent?
Repetition of a certain operation a certain number of time
What are the results:
a⁻ⁿ
a⁰
a⁻ⁿ = 1/aⁿ a⁰ = 1
Find the radical of y=rⁿ
r = ⁿ√y
∀y∈ℝ⁺, ⁿ√y =?
ⁿ√y = y^1/n
Which sign do you choose for the radical when possible?
Positive
xᵐ×xⁿ=?
xᵐ×xⁿ = xᵐ⁺ⁿ