Algebra & Sequences

Algebra might sound complicated, but it is really just using letters to stand for numbers you do not know yet. In the GL 11+ exam, you will need to understand simple expressions, solve equations, and work with number sequences. This lesson teaches you how.

---

What Is Algebra?

In algebra, we use letters (called variables) to represent unknown numbers.

Expression	Meaning
a + 5	A number plus 5
3b	3 times a number
c - 7	A number minus 7
d/4	A number divided by 4
2n + 1	Double a number, then add 1

Key Vocabulary

• Expression: A collection of terms (e.g. 3a + 2b - 5). No equals sign.
• Equation: An expression with an equals sign (e.g. 3a + 2 = 17).
• Variable: A letter representing an unknown number.
• Coefficient: The number in front of a variable (in 5x, the coefficient is 5).
• Term: A single part of an expression (in 3a + 2b - 5, there are three terms: 3a, 2b, and -5).

---

Simplifying Expressions