Term
A product of coefficients and any number of variables with exponents is called a term. Terms that have the same variables with identical exponents for each variables are called like terms.
Example:
3x,axy,4x2yz are terms. 3x+2 is not term: it is a sum of two terms.
3x2y and 7x2y are like terms since both have the same variables x and y with identical exponents: 2 for x and 1 for y.
Remember:
There cannot be any addition or subtraction in a single term.
Since multiplication is associative, rearrangements of variables does not change a term:3xy is same as 3yx.
3x2y and 7xyx are like terms.
GRE數(shù)學(xué)考點介紹：Conditional
Conditional
Probability of event A conditioned on the fact that event B has happened is called the conditional probability and written as P(AIB).
P(AIB)=Probability Both A and B happens/ Probability B happens.
Example:
A six-sided die with faces from 1 to 6 is rolled twice. What is the probability that the face 5 turned up on first try given that the sum of the two faces is 9?
P(sum of faces is 9)=4/36=1/9.
P(face 5 turns up on the first try and sum is 9)=(1/6)*(1/6)=1/36.
P(face 5 turned up on first try given sum is 9)=(1/36)*(1/9)=1/4
Remember:
If P(AIB)=P(A),then two events A and B are independent, that is occurrence of one does not influence the other