Completing the square is a method of rewriting a quadratic expression or equation. 

• A quadratic expression is rewritten in the form  , where , , and are constants and
• A quadratic equation is rewritten in  the form .

A quadratic expression is in factored form when it is written as the product of a constant times two linear factors.

• written in factored form is .
• written in factored form is .

An irrational number is a number that is not rational. This means it cannot be expressed as a positive fraction, a negative fraction, or zero. It cannot be written in the form , where and are integers and .

For example, the numbers and are irrational numbers.

A linear term of an expression has a variable raised to the first power. 

• In the expression, , the linear term is .
• In the expression, , the linear term is .
• In the expression , where , , and are constants, the linear term is .

A perfect square is a number or an expression that is the result of multiplying a number or an expression to itself. In general, the multiplied number is rational and the multiplied expression has rational coefficients.

A quadratic equation is an equation that is equivalent to one of the form , where , , and are constants and .

The quadratic formula is and gives the solutions of the quadratic equation , where , , and are constants and .

A rational number is a number that can be written as a positive fraction, a negative fraction, or zero. It can be written in the form , where and are integers and . 

• 0.7 is a rational number because it can be written as .
• The numbers 0, 3, , and 6.7 are all rational numbers. 

The standard form of a quadratic expression is , where , , and are constants and 0.

A zero of a function is an input that results in an output of 0. In other words, if , then is a zero of .

The zero product property says that if the product of two numbers is 0, then one of the numbers must be 0.