• Distance from the object to the mirror is exactly the same as the image to the mirror
• The object-image line is perpendicular to the mirror surface
• Images are upright but flipped horizontally

A Sequence is a set of things (usually numbers) that are in order.

In an Arithmetic Sequence the difference between one term and the next is a constant.

Example: 1, 4, 7, 10, 13, 16, 19, 22, 25, ...

This sequence has a difference of 3 between each number.

Suppose in an arithmetic sequence:  More...

A "quotient" is the result of a division problem. For example: For 6/3, "2" is the quotient, 6 is the dividend, and 3 is the divisor.

Sometime when dividing, there is something left over, it is called the remainder. For example: For 7/3, "2" is the quotient, 7 is the dividend, 3 is the divisor, and "1" is the remainder. 7/3 = 2 R 1.

dividend = divisor * quotient + remainder

For example:

7 = 3 * 2 + 1

Arithmetic mean (average) = (X₁+X₂+X₃+...+X_n) / n

Geometric mean = (X₁ * X₂ * X₃ * ... * X_N)^1/N