Chapter 8: Problem 37
Is \(f(x)=\left(3 x^{2}-2\right)-(2 x+1)\) a quadratic function? Explain your answer.
Short Answer
Expert verified
Yes, it is a quadratic function because it simplifies to \(3x^2 - 2x - 3\), with \(a = 3 \neq 0\).
Step by step solution
01
Understand the Problem
To determine if the function \(f(x) = (3x^2 - 2) - (2x + 1)\) is quadratic, we need to express it in the standard form of a quadratic function, which is \(ax^2 + bx + c\), where \(a\), \(b\), and \(c\) are constants and \(a eq 0\).
02
Simplify the Expression
Start by expanding the given function: \(f(x) = 3x^2 - 2 - 2x - 1\). Now, combine like terms to simplify the expression.
03
Combine Like Terms
Combine the constants and the linear terms: \(f(x) = 3x^2 - 2x - 3\). This combines the \(-2\) and \(-1\) to get \(-3\).
04
Identify the Standard Form
The simplified expression is \(f(x) = 3x^2 - 2x - 3\). This fits the standard form of a quadratic function \(ax^2 + bx + c\), where \(a = 3\), \(b = -2\), and \(c = -3\).
05
Check the Quadratic Term
Verify that the coefficient \(a\) of the quadratic term \(x^2\) is not zero. As long as \(a eq 0\), the function is considered a quadratic. Here, \(a = 3\), which is not zero.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Standard Form of Quadratic Equation
Understanding the standard form of a quadratic equation is crucial. This form is expressed as \( ax^2 + bx + c \). It provides a framework to easily identify the behavior and characteristics of quadratic functions. Here, \( a \), \( b \), and \( c \) represent real number coefficients. The significance of these components are:
- \( a \) is the coefficient of the \( x^2 \) term. This value is crucial because it determines the parabola's direction—upward when \( a \) is positive, and downward when negative. Additionally, \( a \) must be non-zero for the equation to truly be quadratic.
- \( b \) represents the coefficient of the linear or \( x \) term, impacting the slope and y-intercept.
- \( c \) is the constant term and determines where the parabola crosses the y-axis.
Polynomial Simplification
Simplifying polynomials is key to tackling algebraic expressions effectively. The original expression \((3x^2 - 2) - (2x + 1)\) requires expanding and combining terms in a straightforward manner. Start with:
- Expand the subexpressions: Distribute the subtraction across the brackets which gives \( 3x^2 - 2 - 2x - 1 \).
- Combine like terms: Group terms based on their degree. Here, \( 3x^2 \) stays as is, while the constants \(-2\) and \(-1\) add to \(-3\), and \(-2x\) stands alone as the linear term.
Coefficient Identification
Identifying coefficients in expressions is essential for understanding polynomials' structure. In a quadratic function \( ax^2 + bx + c \), each term's coefficient tells a story about the function's graph and solutions. Consider:
- Coefficient \( a = 3 \): As the leading coefficient, it confirms the parabola is opening upwards and maintains the function's quadratic nature.
- Coefficient \( b = -2 \): This impacts the symmetry and slope of the parabola.
- Constant \( c = -3 \): Demonstrates where the graph intercepts the y-axis.