inverse operation additive inverse pairs of operations that undo each other two numbers that are opposite in value and whose sum is zero multiplicative inverse solution two numbers that when multiplied together equal 1 the value or values of a variable that make an equation a true statement square root perfect square one of two equal factors of a nonnegative number a number that has a rational number as its square root 16 = 4 𝟐𝟓 = 𝟓 𝟐𝟔 ≈ 𝟓. 𝟎𝟗𝟗𝟎𝟏 … radical a symbol ( ) that is used to indicate square roots cube root one of three equal factors of a number rational a number that can be written as the ratio of two integers with a nonzero denominator decimal expansion the representation of a number in the decimal system irrational a real number whose decimal form is non-terminating and non-repeating that cannot be written as a ratio of two integers like terms monomials that have the same variable raised to the same power expression a mathematical phrase involving variables and/or numbers and operation symbols linear equation an equation that can be written in the form ax + b = c where a, b, and c are real numbers and a ≠ 0 equation variable a mathematical sentence that contains an equals sign a letter or symbol used to represent a number scientific notation exponents the number of times a base is used as a factor of repeated multiplication a number that can be written as the ratio of two integers with a nonzero denominator significant digits exponential notation a number where a base is written to some power digits in a decimal number beginning with the first nonzero digit to the right of the decimal and ending with the digit farthest to the right