# Math Vocabulary - I

S
Word Definition Examples
Identity An equation that is true for every value of the variable Always true x + 1 = 1 + x
Identity Property of Addition The sum of any number and zero is that number Anything + 0 = Itself a + 0 = a
Identity Property of Multiplication The product of any number and one is that number Anything x 1 = Itself a • 1 = a
Image The position of a figure after a transformation.
Imaginary Number A number of the form a + bi, where i is the square root of -1 and i2 = -1 √(-4) = 2i
Impossible Event In probability, an event that never happens Getting 4Ľ when you roll one dice is impossible
Improper fraction A fraction where the numerator is larger than the denominator. In arithmetic, you are trained to change these to a mixed number. In Algebra, you should leave it alone.
 7 = 1 ľ 4 improper mixed
IncenterThe point in a triangle where the angle bisectors of the triangle intersect. Click here for an animated example of the incenter.
Independent Events In probability, when the outcome of one event does not affect the outcome of a second event, the events are independent
Independent Variable A variable that does not depend on another variable The input variable For y = x + 3
x is independent
Inductive Reasoning A method used to reach conclusions based on an observed pattern. For the pattern 2, 4, 6, 8 you can induce that since they are all even numbers, the next number must be 10
Inequality One expression that is not equal to another x > 7  means x is greater than 7
-2 < x means negative 2 is less than x
4 < x means x is 4 or bigger
Infinity The concept of something that never ends - infinity is not a number
Integer The whole numbers and their opposites ... - 3, -2, -1, 0, 1, 2, 3, ...
Integral In Calculus, the area between the graph of a line and the x-axis. The process of finding the integral is called integration
Intersect Lines intersect when they cross. The point where they cross is called the intersection.
Interval A portion of the real number line that may or may not include the end points.  The ends of the interval are called the boundaries.
Interval notation A short way to define an interval. Brackets [ or ] are used if the end point is part of the interval. Parentheses ( or ) means the end point is not included in the interval.
For ∞ and - ∞, always use parentheses.
[3, 5) means
3 < x < 5
Inverse Operation Operations that undo each other - they are opposite operations addition and subtraction are inverses
multiplication and division are inverses
squares and square roots are inverses
Inverse Variation A function that can be written in the form xy = k or y = k/x As one variable gets bigger, the other gets smaller
Irrational number A number that cannot be written as a fraction. A decimal that does not truncate (end) or repeat. π = 3.14159...
√7 = 2.6457...
Isometric drawing The drawing of a three-dimensional object that shows the corners.
Isosceles trapezoid A trapezoid whose nonparallel sides are congruent.
The top and bottom are parallel, the sides are the same size, and the diagonals are equal. Isosceles triangle A triangle where at least two sides are congruent Two or more sides equal

Comments, questions, or you just need some help? Send an e-mail to Mrs. Shearer Last Updated: 6/26/2014  