Question

Factorise (a) \(m n+11 m\), (b) \(3 p q-2 p\), (c) \(11 p q-3 q r\), (d) \(4 z x+20 y z\)

Short answer

(a) \(mn + 11m\) (b) \(3pq - 2p\) (c) \(11pq - 3qr\) (d) \(4zx + 20yz\) Answer: (a) \(m(n + 11)\) (b) \(p(3q - 2)\) (c) \(q(11p - 3r)\) (d) \(4z(x + 5y)\)

Step-by-step solution

Identify the GCF of the terms in each expression

We will find the GCF of the terms in each expression to know the common factor to factorise. (a) \(mn + 11m\): The GCF is \(m\) since both terms have \(m\) as a factor. (b) \(3pq - 2p\): The GCF is \(p\) since both terms have \(p\) as a factor. (c) \(11pq - 3qr\): The GCF is \(q\) since both terms have \(q\) as a factor. (d) \(4zx + 20yz\): The GCF is \(4z\) since both terms have \(z\) as a factor and \(4\) is the largest common integer divisor.

Factor the GCF from each expression

Using the GCF identified in Step 1, we will factor out the common factor from each term in the expressions. (a) \(mn + 11m\): Since the GCF is \(m\), we can rewrite the expression as \(m(n + 11)\). (b) \(3pq - 2p\): Since the GCF is \(p\), we can rewrite the expression as \(p(3q - 2)\). (c) \(11pq - 3qr\): Since the GCF is \(q\), we can rewrite the expression as \(q(11p - 3r)\). (d) \(4zx + 20yz\): Since the GCF is \(4z\), we can rewrite the expression as \(4z(x + 5y)\). Now we have factorised the given expressions as follows: (a) \(mn + 11m = m(n + 11)\) (b) \(3pq - 2p = p(3q - 2)\) (c) \(11pq - 3qr = q(11p - 3r)\) (d) \(4zx + 20yz = 4z(x + 5y)\)

Key concepts

Greatest Common Factor

The greatest common factor (GCF) of two or more terms is the largest factor that divides each term evenly. It plays a crucial role in factorization, helping us simplify expressions and make calculations easier. When finding the GCF, look for:

• Common variables: Check for letters (variables) that appear in all terms. If a variable shows up in each term, it can be a part of the GCF.
• Coefficients: Consider the numerical part of each term and find the largest number that divides both or all numbers evenly. This number is included in the GCF.

In the exercise above, for example, when we examined the expression \(mn + 11m\), we found that \(m\) is a common factor in both terms. Identifying the GCF helps in rewriting expressions more compactly, making them less cluttered and more straightforward to manipulate.

Mathematical Expressions

Mathematical expressions are combinations of numbers, variables, and mathematical operations such as addition, subtraction, and multiplication. Understanding the structure of these expressions is essential, as they represent calculations and can be manipulated to solve problems.

For instance, in expressions like \(3pq - 2p\), we look at each component:

• The terms (\(3pq\) and \(-2p\)) are separated by an operation (subtraction in this case).
• There's a mix of numbers (known as coefficients) and letters (variables) like \(p\) and \(q\).

Recognizing these components allows us to apply algebraic techniques, like factorization, to simplify or solve equations. This simplification, as illustrated in the exercise, helps highlight relationships between elements and prepares expressions for further algebraic manipulation.

Algebraic Manipulation

Algebraic manipulation refers to the process of transforming and simplifying mathematical expressions using various algebraic techniques. One of the primary goals is to rewrite expressions in a simpler or more useful form. This could involve operations like factorization, expansion, or rearranging terms.

In the context of factorization, algebraic manipulation focuses on writing an expression as a product of its factors. For example, rewriting \(11pq - 3qr\) as \(q(11p - 3r)\) involves:

• Identifying the common factor \(q\).
• Dividing each term by \(q\) to create a simpler expression within the parentheses.

These manipulations streamline expressions, making them easier to work with and solve. They are fundamental in algebra, allowing us to solve equations, simplify calculations, and understand relationships within mathematical expressions.