GA Milestones Math Grade 8 key terms

A number that can be written as a fraction of two integers, with a nonzero denominator. Its decimal form either ends or repeats in a fixed pattern.

A number that cannot be written as a fraction of two integers. Its decimal form never ends and never repeats, such as the square root of 2.

A decimal whose digits stop after a finite number of places, such as 0.375. Every terminating decimal represents a rational number.

A decimal in which one or more digits repeat forever in a fixed block, often shown with a bar over the repeating part. It represents a rational number.

A number produced by multiplying an integer by itself, such as 49 or 144. Its square root is a whole number.

A number produced by multiplying an integer by itself three times, such as 27 or 64. Its cube root is a whole number.

A value that, when multiplied by itself, gives a stated number. The square root of 81 is 9, and negative 9 also squares to 81.

A value that, when used as a factor three times, gives a stated number. The cube root of 125 is 5 because 5 times 5 times 5 equals 125.

The sign used to indicate a root, with a small index number showing which root is wanted. No index means square root.

A way of writing very large or very small numbers as a number between 1 and 10 multiplied by a power of ten, such as 3.2 times 10 to the sixth.

A small raised number showing how many times the base is used as a factor. In 5 to the third power, 3 is the exponent.

In a power, the number being repeatedly multiplied. In 7 to the fourth power, 7 is the base and 4 is the exponent.

A number formed by multiplying ten by itself a given number of times, such as 1000. Powers of ten shift decimal points when multiplying or dividing.

Rules for combining powers, such as adding exponents when multiplying like bases and subtracting them when dividing. They also cover zero and negative exponents.

A measure of how steep a line is, found as the change in y divided by the change in x between two points on the line.

The point where a graph crosses the vertical axis, occurring where x equals zero. In slope-intercept form it is the value b.

The equation y equals m x plus b, where m is the slope and b is the y-intercept. It makes graphing a line quick.

An equation whose graph is a straight line, often written with variables raised only to the first power. It has a constant rate of change.

How much one quantity changes for each unit change in another. On a graph it equals the slope of the line.

A relationship between two quantities whose ratio stays constant, graphed as a line through the origin. It can be written as y equals k x.

The fixed multiplier k in a proportional relationship y equals k x. It equals the ratio of y to x for every pair of values.

A rate expressed for exactly one unit of the second quantity, such as miles per one hour. It is found by dividing the two quantities.

Two or more linear equations considered together. A solution is an ordered pair that satisfies every equation at once.

The ordered pair or pairs that make all equations in a system true. On a graph it is where the lines intersect.

A way to solve a system by rewriting one equation for a variable and putting that expression into the other equation.

A way to solve a system by adding or subtracting the equations, sometimes after multiplying one, so a variable cancels out.

A rule that assigns exactly one output to each input. Different inputs may share an output, but one input cannot have two outputs.

The value put into a function, often called x. Each input is paired with exactly one output.

The result a function produces from an input, often called y. It depends on the input value chosen.

A function whose graph is a straight line and whose outputs change by a constant amount for each equal step in the inputs.

A movement or change of a figure on a coordinate plane, such as a slide, flip, turn, or size change. It produces a new figure from the original.

A transformation that slides every point of a figure the same distance in the same direction. The figure keeps its size, shape, and orientation.

A transformation that flips a figure over a line, producing a mirror image. Distances and angle measures stay the same.

A transformation that turns a figure about a fixed point by a given angle. The figure keeps its size and shape.

A transformation that enlarges or shrinks a figure by a scale factor from a center point. The image is similar to the original, not necessarily congruent.

Figures with exactly the same size and shape. Their matching sides and angles are equal, and one can be moved onto the other.

Figures with the same shape but possibly different sizes. Matching angles are equal and matching sides are proportional.

The ratio that compares a side length of an image to the matching side length of the original figure. It tells how much a figure was enlarged or shrunk.

The rule that in a right triangle the sum of the squares of the two legs equals the square of the hypotenuse, written a squared plus b squared equals c squared.

The longest side of a right triangle, located opposite the right angle. It is the side labeled c in the Pythagorean theorem.

Either of the two shorter sides of a right triangle that form the right angle. Their squares add to the square of the hypotenuse.

The amount of space a three-dimensional figure occupies, measured in cubic units. Formulas differ by shape, such as cylinder or cone.