# Arithmetic and geometric sequences

A **geometric sequence** is a sequence of numbers where each term is obtained by multiplying the previous term by a **constant ratio**.

In a geometric sequence, the ratio between consecutive terms remains the same. These sequences appear in various mathematical contexts and have practical applications in fields like finance, physics, and computer science!

An **arithmetic sequence** is a sequence of numbers where each term is obtained by adding a **constant difference** to the previous term. In an arithmetic sequence, the difference between consecutive terms remains the same.

Core Assessment | Extended Assessment | Examination Timeline | Scoring System | Passing Marks | Chapter Names |
---|---|---|---|---|---|

Algebraic expressions and equations | Quadratic functions and equations | Exam takes place in May/June | Marking scheme based on accuracy and method | 50 | 1. Number
2. Algebra
3. Geometry and measure
4. Statistics and probability |

Trigonometry and geometry | Probability and statistics | Examination duration is 2 hours and 30 minutes | Marks awarded for correct answers with working shown | 55 | 1. Sets and functions
2. Quadratic functions and equations
3. Vectors
4. Probability |

Let’s explore the concepts of **arithmetic sequences** and **geometric sequences** in the context of Cartesian coordinates:

**Arithmetic Sequences**:An**arithmetic sequence**is a sequence of numbers where each term is obtained by adding a**constant difference**to the previous term.

In the context of Cartesian coordinates, think of an arithmetic sequence as a set of points along a straight line with equal spacing between them.

The x-coordinates (abscissae) of these points form an arithmetic sequence.

For example, consider the sequence of points: ((1, 3), (2, 5), (3, 7), (4, 9), \ldots)Here, the x-coordinates form an arithmetic sequence: 1, 2, 3, 4, …

The constant difference between consecutive x-coordinates is 1.

**Geometric Sequences**:A**geometric sequence**is a sequence of numbers where each term is obtained by multiplying the previous term by a**constant ratio**.

In the context of Cartesian coordinates, think of a geometric sequence as a set of points forming a curve that grows or shrinks exponentially.

The y-coordinates (ordinates) of these points form a geometric sequence.

For example, consider the sequence of points: ((1, 2), (2, 4), (3, 8), (4, 16), \ldots)Here, the y-coordinates form a geometric sequence: 2, 4, 8, 16, …

The constant ratio between consecutive y-coordinates is 2.

In summary, arithmetic sequences involve linear patterns with equal spacing, while geometric sequences exhibit exponential growth or decay. Understanding these concepts can help you analyze patterns and relationships in Cartesian coordinates!

Now, Let’s delve into **arithmetic** and **geometric sequences** in the IGCSE Mathematics syllabus:

**Arithmetic Sequences**:An arithmetic sequence is a sequence of numbers where each term is obtained by adding a**constant difference**to the previous term.

The general form of an arithmetic sequence is:

an=a1+(n−1)d

Here,

(a_n) represents the (n)th term.

d=an+1−an / n+1−n

**Geometric Sequences**:A geometric sequence is a sequence of numbers where the**ratio**between any two consecutive terms is**constant**.

The general form of a geometric sequence is:

an+1=r⋅an

Here,

(a_n) represents the (n)th term.

r=anan+1

Understanding these sequences is crucial for solving problems related to patterns, growth, and series. Practice working with both arithmetic and geometric sequences to strengthen your skills!