An arithmetic sequence is a list of numbers that increases or decreases by a constant amount, called the common difference. The nth term equals first term plus (n−1) times the difference: aₙ = a₁ + (n−1)d. The sum of n terms is Sₙ = n/2 × (first + last). Table of Contents What Is an Arithmetic Sequence? Core Formulas and…

A logarithm answers the question “to what exponent must a base be raised to get a given number?” Mastering the logarithm formulas and rules—especially the change-of-base formula—lets you simplify expressions, solve equations, and evaluate logs on any calculator. Below is a concise, practice-ready guide with clear examples and one compact rules table. What a Logarithm Is (and Why It Matters)…