Grade 7 Math Study Guide Chapter 2 ~ Integers Vocabulary to Know: absolute value: the distance a number is from zero on a number line additive inverse: two integers that are opposites; the sum of an additive inverse and its opposite is zero coordinate plane: a plane in which a horizontal number line and a vertical number line intersect at their zero points; also called a coordinate grid graph: locating the position of a point on the coordinate plane, and drawing a dot at that location based on the ordered pair integer: any number from the set {…, -3, -2, -1, 0, 1, 2, 3,…} negative integer: an integer that is less than zero; negative numbers are written with a – sign opposites: two integers are opposites if they are represented on the number line by points that are the same distance from zero, but on opposite sides of zero; the sum of two opposites is zero ordered pair: a pair of numbers used to locate a point in the coordinate plane; an ordered pair is written in the form (xcoordinate, y-coordinate) origin: the point at which the x-axis and the y-axis intersect in a coordinate plane; the origin is at (0,0) positive integer: an integer that is greater than zero; these numbers are written either with or without a + sign quadrant: one of the four (4) regions into which the two perpendicular lines of the coordinate plane separate the plane x-axis: the horizontal axis in a coordinate plane x-coordinate: the first number in an ordered pair; it corresponds to a number on the x-axis y-axis: the vertical number in a coordinate plane y-coordinate: the second number in an ordered pair; it corresponds to a number on the y-axis Rules to Remember: Integers and Absolute Value Integers less than zero are negative numbers. Integers greater than zero are positive numbers. When writing the absolute value of a positive or negative number, two vertical bars are used. The symbol for absolute value of the integer 3 is l3l. The Coordinate Plane The coordinate plane is used to locate points; the horizontal number line is the x-axis; the vertical line is the yaxis; their intersection is called the origin. Points are located using ordered pairs. The first number in an ordered pair is the x-coordinate; the second number is the y-coordinate. The coordinate plane is separated into four regions called quadrants. The quadrants are labeled using Roman Numerals. Adding & Subtracting Integers To add integers with the same sign, add their absolute values. The sum is: o positive (+) if both integers are positive (+) o negative (-) if both integers are negative (-) To add integers with different signs, subtract their absolute values. The sum is: o Positive (+) if the positive (+) integer’s absolute value is greater o Negative (-) if the negative (-) integer’s absolute value is greater To add integers, sometimes it is helpful to use a number line. To subtract an integer, add its opposite Multiply Integers The product of two integers with the same sign is positive (+). The product of two integers with different signs is negative (-). Divide Integers The quotient of two integers with the same sign is positive (+). The quotient of two integers with different signs is negative (-).