Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GRE Math > Key Math Notes > Flashcards

Key Math Notes Flashcards

You may prefer our related Brainscape-certified flashcards:
GRE® Vocabulary flashcards GRE® Psychology flashcards
1
Q

Dilution or Mixture

A

Where w=weaker solution,

s=stronger solution,

and d=desired solution

______________

(w%-d%)w = (s%-d%)s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

GROUP

A

Group 1

+ Group 2

+ Neither

  • Both

Total #

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Permutation

of ways to arrange elements sequentially (with repitition)

A

nPk=

__n!_\_

(n - k)!

n= # in the large group

k= # being arranged

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

COMBINATION

When the order in an arrangement of the smaller group being drawn from the larger group doesn’t matter

A

nCk =

_\_n!__

k! (n - k)!

n = # in larger group

k = # being chosen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

COMBINED WORK

A

The inverse of the time it would take everyone working together equals the sum of the inverse of the times it would take each owrking individually

1/r + 1/s = 1/t

r and s = the time it would take individuals working seperately

t = the time it would take them working together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

P E M D A S

A

Parantheses

Exponents (or radicals)

Multiplication & Division

(from left to right)

Addition & Subtraction

(from left to right)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Multiples of 3

A

sum of digits is multiple of 3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Multiples of 4

A

last two digits are a multiple of 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Multiples of 6

A

Even number whose sume is multiple of 3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Multiples of 9

A

sum of digits is multiple of 9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Multiples of 12

A

a multiple of both 3 and 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Max and Minimum Sides of a triangle

A

The third side of a triangle is between the positive difference and sum of the other two sides.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Regular Polygon Angles

A

n = # of sides

Sum of interior angles:

(n - 2) x 180

Degree of one angle:

(n - 2) x 180

n

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

LENGTH of an ARC

A

ARC =

θ = angle

(θ / 360) x 2πr

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

AREA of a SECTOR

A

SECTOR =

θ = angle

(θ / 360) x πr2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

ARC

SECTOR

SEGMENT

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

(xa)(xb)

A

xa+b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

xa / xb

A

xa-b

19
Q

(xa)b

A

xab

20
Q

0x

A

0

21
Q

x0

A

1

22
Q

00

A

Undefined

23
Q

x-2

A

1 / x2

24
Q

x1/3

A

3√x

25
Q

x1/2

A

√x

26
Q

√x + √x

A

2√x

27
Q

(a√b)(c√d)

A

(ab)(√b+d)

28
Q
A

isosceles triangle

2 angles are the same

2 sides are the same

29
Q
A

Equalateral Triangle

All sides are equal

All angles are 60o

30
Q
A

Similar Triangles

Corresponding angles are equal

Sides are proportional

31
Q

Pythagorean Theorem

A

With right triangles only:

a2 + b2 = c2

32
Q

Special Right Angles

Side proportions (4)

A

3 : 4 : 5

5 : 12 : 13

30o - 60o - 90o

= 1 : √3 : 2

45o - 45o - 95o

= 1 : 1 : √2

33
Q

SLOPE

A

RISE / RUN

Change in Y / Change in X

34
Q

SIMPLE

INTEREST

A

Interest Earned (I) =

Principle (P)

x interest rate (r)

x time, in years (t)

I = Prt

35
Q

COMPOUND

INTEREST

A

Interest Earned (I) =

Principle (P)

Interest Rate (r)

time, in years (t)

of times compounded annually (c)

I = P ( 1 + r/c)tc

36
Q

Counting consecutive numbers

A

A => B =

B - A + 1

37
Q

Sum of Consecutive numbers

A

Sum = Average x # of terms

A => B

(A + B) / 2 = Average of terms

B - A + 1 = # of terms

(A + B) / 2

38
Q

Recognize this Polynomial

ab + ac

A

a (b + c)

39
Q

Recognize this Polynomial

a2 + 2ab + b2

A

(a + b)2

40
Q

Recognize this Polynomial

a2 - 2ab + b2

A

(a - b)2

41
Q

Recognize this Polynomial

a2 - b2

A

(a + b)(a - b)

42
Q

WEIGHTED

AVERAGE

A

Group A Average = x

Group B Average = y

Group A is z times as big as Group B

(zx + (1)y) / (z+1)

43
Q

COMMON FACTORS

eg: 135 and 225

A

1st: find the prime factors in each #

135 = 3 x 3 x 3 x 5

225 = 3 x 3 x 5 x 5

2nd: find the prime factors they have in common

3 x 3 x 5

3rd: multiply these common factors in every combination

3 x 3, 3 x 5, 3 x 3 x 5

So, common factors are 3, 5, 9, 15, 45

44
Q

STANDARD

DEVIATION

A
  1. Find the mean of the set
  2. Find the difference between the mean and each value
  3. Square each of the differences
  4. Find the average of the squared differences (3)
  5. Take the positive square root of the average (4)

GRE Math (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions