# Pre-Algebra – Quick Reference Sheet

Properties of Algebra The Cartesian Coordinate System
 Addition Multiplication Identity The additive identity is 0 The multiplicative identity is 1 Inverse The additive inverse of a is  If , the multiplicative inverse of a is  Associative  Commutative  Distributive and Property of Inequalities

When multiplying or dividing each side of an inequality by a positive number an equivalent inequality is produced. When multiplying or dividing each side of an inequality by a negative number the equivalent inequality is produced by reversing the direction of the inequality. Order of Operations (PENDAS)

1. Parentheses
2. Exponents
3. Multiplication and Division The Cartesian plane contains two axis, the x-axis and y-axis. The coordinates of point are written (x,y). You can tell what quadrant a point lies in by the signs of the coordinate. Quadrant 1: (+,+) Quadrant 2:(-,+) Quadrant 3:(-,-) Quadrant 4:(+,-)
 Probability

Definitions

Probability: the likelihood that an event will occur
Equation Multiplication Rule: When there are multiple independent events happening together the individual probabilities are multiplied together. Such events are drawing two cards from a deck or flipping a coin.
Example:A coin flipped and a 6-sided die is rolled at the same time. What is the probability of getting heads and 3? and  Addition Rule: When there are two mutually exclusive events (outcomes cannot happen at the same time), add the two individual probabilities together.
Example: A bag of marbles contains 1 green, 3 red, and 2 blue marbles. One marble is drawn. What is the probability that it is either green or blue? and  Ratios and Percentages
Definitions

Ratio: when two qualities are divided as a means of comparing them
Percentage: a fraction (or ration) out of 100
Converting From Fraction to a Percentage

To convert a fraction to a percentage first write the fraction as a decimal then multiply the decimal by 100 and add the percent symbol (%).
Example: This space was intentionally left blank for spacing purposes.