Chapter 9: Problem 2
Rewrite each quadratic equation in general form if necessary. For each equation, identify the values of \(a, b\), and \(c\). a. \(2 x^{2}+3 x-7=0\) b. \(x^{2}+6 x=-11\) (a) c. \(-3 x^{2}-4 x+12=0\) d. \(18-4.9 x^{2}+47 x=0\) (a) e. \(-16 x^{2}+28 x+10=57\)
Short Answer
Expert verified
a) \(a=2\), \(b=3\), \(c=-7\); b) \(a=1\), \(b=6\), \(c=11\); c) \(a=-3\), \(b=-4\), \(c=12\); d) \(a=-4.9\), \(b=47\), \(c=18\); e) \(a=-16\), \(b=28\), \(c=-47\).
Step by step solution
01
Confirm equation a is in general form
The equation given is \(2x^2 + 3x - 7 = 0\). This is already in the general quadratic form \(ax^2 + bx + c = 0\).
02
Identify coefficients for equation a
From the equation \(2x^2 + 3x - 7 = 0\), we identify the coefficients as \(a = 2\), \(b = 3\), and \(c = -7\).
03
Rewrite equation b in general form
The original equation is \(x^2 + 6x = -11\). To rewrite it, add 11 to both sides: \(x^2 + 6x + 11 = 0\).
04
Identify coefficients for equation b
In the equation \(x^2 + 6x + 11 = 0\), the coefficients are \(a = 1\), \(b = 6\), and \(c = 11\).
05
Confirm equation c is in general form
The equation given is \(-3x^2 - 4x + 12 = 0\). It is already in the general form \(ax^2 + bx + c = 0\).
06
Identify coefficients for equation c
In \(-3x^2 - 4x + 12 = 0\), the coefficients are \(a = -3\), \(b = -4\), and \(c = 12\).
07
Rewrite equation d in general form
The original equation is \(18 - 4.9x^2 + 47x = 0\). Rearrange it: \(-4.9x^2 + 47x + 18 = 0\).
08
Identify coefficients for equation d
The equation is \(-4.9x^2 + 47x + 18 = 0\), so \(a = -4.9\), \(b = 47\), and \(c = 18\).
09
Rewrite equation e in general form
The original equation is \(-16x^2 + 28x + 10 = 57\). Subtract 57 from both sides to get: \(-16x^2 + 28x - 47 = 0\).
10
Identify coefficients for equation e
From \(-16x^2 + 28x - 47 = 0\), the coefficients are \(a = -16\), \(b = 28\), and \(c = -47\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
General Form
The general form of a quadratic equation is an essential concept in understanding how to work with quadratics. It is typically written as \( ax^2 + bx + c = 0 \). This form includes three main components:
- Quadratic term: This is the \( ax^2 \) part, where \( a \) is a coefficient that multiplies the squared variable \( x^2 \).
- Linear term: This is the \( bx \) part, where \( b \) is a coefficient of the variable \( x \).
- Constant term: The \( c \) part is just a constant number, not attached to a variable.
Coefficients
Coefficients are numbers that multiply variables in an equation, and they play a critical role in defining the behavior and solutions of quadratic equations. In the general form \( ax^2 + bx + c = 0 \), the coefficients \( a \), \( b \), and \( c \) have specific functions:
- Coefficient \( a \): Determines the direction and curvature of the parabola (upward if \( a > 0 \), and downward if \( a < 0 \)).
- Coefficient \( b \): Affects the vertex location and shape of the parabola, influencing its horizontal placement on the graph.
- Constant \( c \): Represents the value of the equation when \( x = 0 \), effectively marking the y-intercept on a graph.
Rewrite Equations
Rewriting equations into general form is a common algebraic technique that helps simplify the problem-solving process. Sometimes quadratic equations do not initially appear in their general form, so we need to manipulate them algebraically to reformat them. For example, in the equation \( x^2 + 6x = -11 \), we can rewrite it as \( x^2 + 6x + 11 = 0 \) by adding 11 to both sides. This form makes identifying coefficients and solving the equation more straightforward.Rewriting involves:
- Transposing terms: Move terms from one side to the other to centralize all expressions.
- Arranging terms: Align the equation in the \( ax^2 + bx + c \) structure.
Mathematics Education
Mathematics education involving quadratic equations focuses on developing strong problem-solving skills and conceptual understanding. Learning to identify and work with terms like the general form, coefficients, and rewriting equations enhances a student's ability to tackle more complex math tasks.
In an educational setting, studying quadratic equations prepares students for advanced mathematical topics, such as:
- Calculus: Quadratics are foundational for understanding derivatives and integrals.
- Physics: Many physical phenomena, like projectile motion, are modeled using quadratic equations.
- Engineering: Quadratics appear in various engineering calculations, making them vital in practical applications.