Math Notation Flashcards
≠
not equal sign
Inequality
5 ≠ 4
5 is not equal to 4
=
equals sign
Equality
5 = 2+3
5 is equal to 2+3
≈
approximately equal
approximation
x ≈ y means x is approximately equal to y
>
inequality
greater than
5 > 4
5 is greater than 4
inequality
less than
4 < 5
4 is less than 5
≥
inequality
greater than or equal to
5 ≥ 4,
x ≥ y means x is greater than or equal to y
≤
less than or equal to
4 ≤ 5,
x ≤ y means x is less than or equal to y
( )
parentheses
calculate expression inside first
2 × (3+5) = 16
[ ]
Brackets
calculate expression inside first
[(1+2)×(1+5)] = 18
+
plus sign
Addition
1 + 1 = 2
−
minus sign
Subtraction
2 − 1 = 1
±
plus - minus
both plus and minus operations
3 ± 5 = 8 or -2
*
Asterisk
Multiplication
2 * 3 = 6
×
times sign
Multiplication
2 × 3 = 6
⋅
multiplication dot
Multiplication
2 ⋅ 3 = 6
÷
division sign / obelus
Division
6 ÷ 2 = 3
/
division slash
Division
6 / 2 = 3
—
horizontal line
division / fraction
mod
Modulo
remainder calculation
7 mod 2 = 1
.
Period
decimal point, decimal separator
2.56 = 2+56/100
a^b
Caret
Exponent
2 ^ 3 = 8
√a
square root
√a ⋅ √a = a
√9 = ±3
3√a (3 superindex)
cube root
3√a ⋅ 3√a ⋅ 3√a = a
3√8 = 2
n√a (n superindex)
“n-th root (radical)
for n=3, n√8 = 2”
%
Percent
1% = 1/100
10% × 30 = 3
‰
Per-mille
1‰ = 1/1000 = 0.1%
10‰ × 30 = 0.3
ppm
Per-million
1ppm = 1/1000000
10ppm × 30 = 0.0003
ppb
Per-billion
1ppb = 1/1000000000
10ppb × 30 = 3×10-7
∠
Angle
formed by two rays
∠ABC = 30°
°
Degree
1 turn = 360°
α = 60°
deg
Degree
1 turn = 360deg
α = 60deg
≅
congruent to
equivalence of geometric shapes and size
∆ABC≅ ∆XYZ
~ (geometry)
Similarity
same shapes, not same size
∆ABC~ ∆XYZ
Δ
Triangle
triangle shape
ΔABC≅ ΔBCD
|x-y|
Distance
distance between points x and y
x-y | = 5
π
pi constant
π = 3.141592654…
c = π⋅d = 2⋅π⋅r
rad
Radians
radians angle unit
360° = 2π rad
c
Radians
radians angle unit
360° = 2π c
x
x variable
unknown value to find
when 2x = 4, then x = 2
≡
Equivalence
identical to
≜
equal by definition
:=
equal by definition
~
approximately equal
weak approximation
11 ~ 10
≈
approximately equal
Approximation
sin(0.01) ≈ 0.01
∝
proportional to
y ∝ x when y = kx, k constant
∞
Lemniscate
infinity symbol
≪
much less than
1 ≪ 1000000
≫
much greater than
1000000 ≫ 1
{ }
Braces
set
⌊x⌋
floor brackets
rounds number to lower integer
⌊4.3⌋ = 4
⌈x⌉
ceiling brackets
rounds number to upper integer
⌈4.3⌉ = 5
x!
exclamation mark
Factorial
4! = 123*4 = 24
x |
vertical bars
absolute value
-5 | = 5
f (x)
function of x maps values of x to f(x)
f (x) = 3x+5
(f ∘ g)
function composition (f ∘ g) (x) = f (g(x))
f (x)=3x,g(x)=x-1 ⇒(f ∘ g)(x)=3(x-1)
(a,b)
open interval (a,b) = {x | a < x < b}
x∈ (2,6)
[a,b]
closed interval
[a,b] = {x | a ≤ x ≤ b}
x ∈ [2,6]
∆
Delta
change / difference
∆t = t1 - t0
∑
Sigma
summation - sum of all values in range of series
∑ xi= x1+x2+…+xn
∑∑
Sigma
double summation
∑+∑
∏
capital pi
product - product of all values in range of series
∏ xi=x1∙x2∙…∙xn
e
Euler’s number
e = 2.718281828…
e = lim (1+1/x)x , x→∞
γ
Euler-Mascheroni constant
γ = 0.5772156649…
φ
golden ratio constant
·
Dot
scalar product
a · b
×
Cross
vector product
a × b
⊗
tensor product
tensor product of A and B
A ⊗ B
[ ]
Brackets
matrix of numbers
|| x ||
double vertical bars
norm
AT
Transpose
matrix transpose
(AT)ij = (A)ji