Chapter 8: Problem 17
Factor each of the following as completely as possible. If the polynomial is not factorable, say so. $$2 y^{2}-y-6$$
Short Answer
Expert verified
(y - 2)(2y + 3)
Step by step solution
01
Identify the polynomial structure
The given polynomial is quadratic: \(2y^2 - y - 6\). It has the general form of a quadratic equation: \(ax^2 + bx + c\), where \(a = 2\), \(b = -1\), and \(c = -6\).
02
Multiply the leading coefficient by the constant term
Multiply the leading coefficient \(a\) and the constant term \(c\). In this case, multiply \(2\) and \(-6\): \(2 \times -6 = -12\).
03
Find two numbers that multiply to the product and sum to the middle coefficient
We need to find two numbers that multiply to \(-12\) and sum to \(-1\) (the middle coefficient). These numbers are \(-4\) and \(3\) since \(-4 \times 3 = -12\) and \(-4 + 3 = -1\).
04
Rewrite the middle term using the two numbers
Rewrite the polynomial by splitting the middle term \(-y\) using \(-4\) and \(3\): \(2y^2 - 4y + 3y - 6\).
05
Factor by grouping
Group the terms in pairs: \((2y^2 - 4y) + (3y - 6)\). Factor out the greatest common factor (GCF) from each pair. From the first group, factor out \(2y\): \(2y(y - 2)\). From the second group, factor out \(3\): \(3(y - 2)\).
06
Factor out the common binomial
The expression can now be written as \(2y(y - 2) + 3(y - 2)\). Factor out the common binomial factor \((y - 2)\): \((y - 2)(2y + 3)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Equations
A quadratic equation is a polynomial equation of the form \(ax^2 + bx + c \). Here, \(a \), \(b \), and \(c \) are constants, where \(a \) should never be zero as it would then not be quadratic. Quadratic equations can appear in many different forms, such as \(2y^2 - y - 6 \).
To solve quadratic equations, we typically use techniques like:
In this problem, we're using factoring because it's usually the simplest method for simpler quadratics.
To solve quadratic equations, we typically use techniques like:
- Factoring
- Completing the square
- Quadratic formula: \[ x = \frac {-b \pm \sqrt {b^2 - 4ac}}{2a} \]
In this problem, we're using factoring because it's usually the simplest method for simpler quadratics.
Polynomial Factorization
Polynomial factorization is the process of expressing a polynomial as a product of its factors.
These factors can be other polynomials or simpler expressions.
For example, for the quadratic polynomial \(2y^2 - y - 6 \), we see that it factors into \((y - 2)(2y + 3) \). Factoring helps in solving polynomial equations and understanding their roots more easily.
Here are some points to remember:
Knowing the basic steps and practicing it repeatedly is key to mastering polynomial factorization.
These factors can be other polynomials or simpler expressions.
For example, for the quadratic polynomial \(2y^2 - y - 6 \), we see that it factors into \((y - 2)(2y + 3) \). Factoring helps in solving polynomial equations and understanding their roots more easily.
Here are some points to remember:
- Identify the basic structure of the polynomial.
- Look for common factors.
- Use techniques like grouping and splitting terms to factorize fully.
Knowing the basic steps and practicing it repeatedly is key to mastering polynomial factorization.
Algebraic Expressions
An algebraic expression is a mathematical phrase that can contain numbers, variables, and operators (like +, -, *, and /). In the quadratic equation given in the exercise, \(2y^2 - y - 6 \), we have:
Combining like terms and simplifying expressions are fundamental toward solving algebraic equations. Breaking down these expressions into manageable parts makes it easier to find solutions.
Remember:
- Variables: \(y \)
- Coefficients: \(2 \), \(-1 \) (for \(-y \)), and \(-6 \)
Combining like terms and simplifying expressions are fundamental toward solving algebraic equations. Breaking down these expressions into manageable parts makes it easier to find solutions.
Remember:
- Always follow the order of operations (PEMDAS/BODMAS: Parentheses/Brackets, Exponents/Orders, Multiplication, and Division (left-to-right), Addition and Subtraction (left-to-right))
- Simplify step by step to avoid mistakes.