Chapter 3: Problem 29
Solve each equation. For equations with real solutions, support your answers graphically. $$x(14 x+1)=3$$
Short Answer
Expert verified
The solutions are \( x = \frac{3}{7} \) and \( x = -\frac{1}{2} \).
Step by step solution
01
Expand the Equation
Expand the given equation \( x(14x + 1) = 3 \) to a standard quadratic form. Distribute \( x \) inside the parentheses to get \( 14x^2 + x = 3 \).
02
Rearrange into Standard Form
Rearrange the expanded equation into the standard quadratic form \( ax^2 + bx + c = 0 \). Move 3 to the left side to get \( 14x^2 + x - 3 = 0 \).
03
Identify Coefficients
Identify the coefficients from the standard form equation \( 14x^2 + x - 3 = 0 \). Here, \( a = 14 \), \( b = 1 \), and \( c = -3 \).
04
Apply the Quadratic Formula
Use the quadratic formula \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \) to find the solutions. Substitute the coefficients into the formula: \( x = \frac{-1 \pm \sqrt{1^2 - 4 \cdot 14 \cdot (-3)}}{2 \cdot 14} \).
05
Simplify the Discriminant
Calculate the discriminant \( b^2 - 4ac \). For this equation, \( 1 - 4 \cdot 14 \cdot (-3) = 1 + 168 = 169 \).
06
Calculate the Square Root
Find the square root of the discriminant: \( \sqrt{169} = 13 \).
07
Solve for x
Substitute the square root back into the quadratic formula: \( x = \frac{-1 \pm 13}{28} \). This gives two possibilities: \( x = \frac{-1 + 13}{28} = \frac{12}{28} = \frac{3}{7} \) and \( x = \frac{-1 - 13}{28} = \frac{-14}{28} = -\frac{1}{2} \).
08
Graphical Verification
To graphically verify, plot the quadratic equation \( y = 14x^2 + x - 3 \) on a coordinate plane. Notice that the curve intersects the x-axis at \( x = \frac{3}{7} \) and \( x = -\frac{1}{2} \), confirming the solutions.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Formula
The Quadratic Formula is a powerful tool that helps find solutions to quadratic equations, which are equations of the form \( ax^2 + bx + c = 0 \). Quadratic equations have coefficients \( a \), \( b \), and \( c \) that determine their shape and position when graphed.
- The formula itself is: \( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \).
- It provides solutions by calculating the points where the parabola (graph) intersects the x-axis, known as the roots.
- The \( \pm \) symbol means there can be two solutions: one with addition and one with subtraction.
Discriminant
The Discriminant is an important part of the Quadratic Formula. It is represented by \( b^2 - 4ac \) and helps you determine the nature of the roots of the quadratic equation.
- If the Discriminant is positive, there are two distinct real roots.
- If it is zero, it means there is one real root, also known as a repeated or double root.
- If the Discriminant is negative, then there are no real roots, but two complex roots instead.
Graphical Solution
A Graphical Solution involves plotting the quadratic equation on a graph to visually identify the roots. Here, we graph the equation \( y = 14x^2 + x - 3 \) as a parabola.
- The x-intercepts, where the curve meets the x-axis, indicate the real solutions of the equation.
- In our example, these points were \( x = \frac{3}{7} \) and \( x = -\frac{1}{2} \), exactly matching the results from the Quadratic Formula.
- Graphing helps in understanding the concept of roots visually, making abstract math more tangible.
Standard Form of Quadratic
The Standard Form of a Quadratic Equation is \( ax^2 + bx + c = 0 \). Converting equations into this form makes them easier to analyze and solve using formulas and graphical methods.
- "a" represents the coefficient of \( x^2 \), responsible for the parabola's "width" and direction (upward or downward).
- "b" is the linear coefficient influencing the tilt and orientation of the parabola.
- "c" is the constant term that determines the y-intercept of the graph.