The Factors Of X2-8xy+15y2 Are

Factoring Quadratic Expressions: Unveiling the Factors of x² - 8xy + 15y²

Understanding how to factor quadratic expressions is a fundamental skill in algebra. This ability is crucial for solving quadratic equations, simplifying algebraic fractions, and tackling more advanced mathematical concepts. This comprehensive guide will delve into the process of factoring, focusing specifically on the expression x² - 8xy + 15y², explaining the steps involved and providing a deeper understanding of the underlying principles. We'll explore different factoring techniques and address common questions to solidify your understanding.

Introduction: What is Factoring?

Factoring, in the context of algebra, involves breaking down a mathematical expression into simpler expressions that, when multiplied together, produce the original expression. Think of it like reverse multiplication. For example, factoring the number 12 might involve breaking it down into its prime factors: 2 x 2 x 3. Similarly, factoring an algebraic expression involves finding the simpler expressions that, when multiplied, result in the given expression. This is particularly important for quadratic expressions, which are expressions of the form ax² + bx + c, where 'a', 'b', and 'c' are constants.

Understanding the Quadratic Expression: x² - 8xy + 15y²

Our target expression, x² - 8xy + 15y², is a quadratic expression involving two variables, x and y. It's a trinomial (meaning it has three terms). The goal is to find two binomial expressions (expressions with two terms) that, when multiplied, yield x² - 8xy + 15y².

Step-by-Step Factoring Process

We'll use the method of factoring trinomials by finding two numbers that add up to the coefficient of the middle term (-8) and multiply to the product of the coefficients of the first and last terms (1 x 15 = 15).

1. Identify the Coefficients: In our expression, x² - 8xy + 15y², the coefficients are:

   • a = 1 (coefficient of x²)
   • b = -8 (coefficient of xy)
   • c = 15 (coefficient of y²)

2. Find Two Numbers: We need to find two numbers that:

   • Add up to -8 (the value of b)
   • Multiply to 15 (the value of c)

   Let's consider the factors of 15: 1 and 15, 3 and 5, -1 and -15, -3 and -5. The pair -3 and -5 satisfies both conditions: -3 + (-5) = -8 and (-3) x (-5) = 15.

3. Rewrite the Expression: Now, we rewrite the middle term (-8xy) as the sum of -3xy and -5xy:

   x² - 3xy - 5xy + 15y²

4. Factor by Grouping: We group the terms in pairs and factor out the greatest common factor (GCF) from each pair:

   x(x - 3y) - 5y(x - 3y)

5. Factor out the Common Binomial: Notice that (x - 3y) is a common factor in both terms. We factor it out:

   (x - 3y)(x - 5y)

Therefore, the factors of x² - 8xy + 15y² are (x - 3y) and (x - 5y).

Verification: To verify our answer, we can multiply the factors back together using the FOIL method (First, Outer, Inner, Last):

(x - 3y)(x - 5y) = x² - 5xy - 3xy + 15y² = x² - 8xy + 15y²

This confirms that our factoring is correct.

Alternative Factoring Methods

While the above method is widely applicable, other methods can be used to factor quadratic expressions, particularly when the coefficient of the x² term (a) is not equal to 1. These include:

• AC Method: This method involves multiplying 'a' and 'c', finding two numbers that add up to 'b' and multiply to 'ac', and then rewriting the expression before factoring by grouping.

• Trial and Error: This method involves systematically trying different combinations of binomial factors until you find the pair that multiplies to the original expression. This method becomes less efficient as the coefficients become larger.

Explanation of the Underlying Mathematical Principles

The ability to factor quadratic expressions stems from our understanding of the distributive property of multiplication over addition: a(b + c) = ab + ac. Factoring is essentially the reverse process. By identifying common factors and manipulating the expression, we're effectively applying the distributive property in reverse to break down the expression into its constituent factors. The success of these methods hinges on our ability to identify numerical relationships between the coefficients of the terms in the quadratic expression.

Frequently Asked Questions (FAQ)

• What if the expression can't be factored? Not all quadratic expressions can be factored using integers. In such cases, the quadratic formula or other methods are needed to find the roots of the equation.

• How do I factor quadratics with a leading coefficient other than 1? Methods like the AC method or trial and error become necessary when the leading coefficient is not 1. These methods require a more systematic approach to finding the appropriate binomial factors.

• What are the applications of factoring quadratic expressions? Factoring is essential for solving quadratic equations, simplifying algebraic fractions, finding the roots of a quadratic function (x-intercepts), and graphing quadratic functions. It forms the foundation for many advanced mathematical concepts.

• Can I use factoring to solve quadratic equations? If a quadratic equation is in the form ax² + bx + c = 0 and you can factor the left side, setting each factor equal to zero will provide the solutions for x.

• Are there online tools to help with factoring? Yes, many online calculators and websites can assist with factoring quadratic expressions and other algebraic manipulations. However, understanding the underlying principles is crucial for true comprehension and application of the concept.

Conclusion: Mastering the Art of Factoring

Factoring quadratic expressions like x² - 8xy + 15y² is a crucial skill in algebra. The ability to break down complex expressions into simpler ones is essential for problem-solving in many areas of mathematics and science. By understanding the steps involved, the underlying mathematical principles, and exploring different methods, you can confidently tackle a wide range of factoring problems. Remember that practice is key to mastering this valuable skill. Work through numerous examples, and don't hesitate to review the concepts and methods as needed to build a solid foundation in algebra. With persistent effort, you will become proficient in factoring and unlock a deeper understanding of the world of algebraic expressions.