Perimeter
Perimeter is the distance all the way around the outside of a flat shape. Add the lengths of all the sides. For a rectangle, P = 2l + 2w. Perimeter uses length units like feet or meters.
-
-
Properties of Numbers
The properties of numbers are rules that are always true for adding and multiplying: the commutative, associative, identity, inverse and zero properties. They tell you when you can change the order or grouping without changing the answer.
-
Absolute Value Inequalities
To solve an absolute value inequality, get the absolute value alone, then rewrite it. |x| < 3 means −3 < x < 3 (an “and” inequality). |x| > 3 means x < −3 or x > 3 (an “or” inequality).
-
Absolute Value Equations
To solve an absolute value equation, get the absolute value alone, then split it into two equations. For example, |x − 2| = 5 means x − 2 = 5 or x − 2 = −5, so x = 7 or x = −3.
-
Compound Inequalities
A compound inequality is two inequalities joined by “and” or “or.” An “and” inequality, like −2 < x ≤ 3, is true where both parts are true. An “or” inequality is true where at least one part is true.
-
Literal Equations
A literal equation is an equation with two or more variables, like a formula. To solve it for one variable, get that variable alone with inverse operations. For example, solving d = rt for t gives t = d/r.
-
Equations with Variables on Both Sides
To solve equations with variables on both sides, get all the variable terms on one side and all the numbers on the other. For example, 5x + 2 = 3x + 10 becomes 2x + 2 = 10, so x = 4.
-
Rational and Irrational Numbers
Rational and irrational numbers are the two kinds of real numbers. A rational number is any number you can write as a fraction of two integers, like or . Its decimal either ends or repeats. An irrational number cannot be written as a fraction. Its decimal goes on forever with no repeating pattern, like and…
-
Scientific Notation
Scientific notation is a short way to write very large or very small numbers. You write the number as a value from 1 up to (but not including) 10, times a power of 10. For example, 4,500,000 in scientific notation is , and 0.00032 is . Before this lesson: You should know powers of 10…
-
Cube Roots
A cube root of a number is the value you multiply by itself three times to get that number. The cube root of 27 is 3, because . We write it as . Unlike square roots, negative numbers have cube roots, so . Before this lesson: You should know cubes from Exponents and the ideas…