GRE Quant Flashcards
(a+b)^3=
a^3 + 3a^2b + 3b^2a + b^3
(a-b)^3=
a^3 - 3a^2b + 3ab^2 - b^3
x^a+x^b =
x^(a+b)
(x^a)^b=
x^(ab)
x^a•y^a=
(xy)^a
|r + s| ? |r| + |s|
≤
|r||s| ? |rs|
=
Simple interest formula
V=P(1+(rt/100))
Annually compounded interest formula
V=P(1+(r/100))^t
Interest compounded n times annually
V=P(1+(r/100))^nt
Area of a trapezoid
½(b1+b2)(h)
Number of permutations of n objects
n!
Number of permutations of size k, a subset of a set of size n
n!/(n-k)!
Number of unordered permutations of size k, a subset of a set of size n
n!/(n-k)!k!
Length of an arc of angle size a
(a/360)2πr
Area of a sector of angle size a
(a/360)πr^2
P(E or F) when not mutually exclusive
P(E)+P(F)-P(E & F)
P(E or F) if mutually exclusive
P(E)+P(F)
P(E&F) if independent
P(E)P(F)
If you simplify a linear equation and get x=x, then
it’s an identity true for all x
When do you reverse the inequality sign?
When multiplying or dividing by a negative number
The interior angles of an n-gon sum to how many degrees?
(n-2)(180)
The interior angles of a regular n-gon are all how many degrees?
(180(n-2))/n
Standardization of a data set is the same as
finding the z-scores
Is sample standard deviation the same as standard deviation?
no
What are the valid triangle congruency sets?
SSS, SAS, ASA, AAS
Pi can be approximated as
22/7 or 3.14
A what is the relationship between the weighted mean and the arithmetic mean?
It’s the same thing but instead of 7+7+7 it’s 3•7
What are the side ratios for a 45° right triangle?
1/1/root2
What are the side ratios for a 30°/60° right triangle?
1/2/root3
The coordinates of point B that is symmetric with point A=(a,b) across the y-axis are:
(-a,b)
The coordinates of point B that is symmetric with point A=(a,b) across the x-axis are:
(a,-b)
The coordinates of point B that is symmetric with point A=(a,b) across the origin are:
(-a,-b)
The coordinates of point B that is symmetric with point A=(a,b) across the line y=x are:
(b,a)
