Chapter 3: Problem 44
Solve each equation. For equations with real solutions, support your answers graphically. $$11 x^{2}-3 x+2=4 x+1$$
Short Answer
Expert verified
The solutions are \(x = \frac{7 + \sqrt{5}}{22}\) and \(x = \frac{7 - \sqrt{5}}{22}\).
Step by step solution
01
Rewrite the Equation
Start by rearranging the given equation so that one side is zero. The original equation is \(11x^2 - 3x + 2 = 4x + 1\). Subtract \(4x + 1\) from both sides to get: \[11x^2 - 3x + 2 - 4x - 1 = 0\] which simplifies to \[11x^2 - 7x + 1 = 0\].
02
Use the Quadratic Formula
The quadratic formula is \(x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\). For the equation \(11x^2 - 7x + 1 = 0\), identify \(a = 11\), \(b = -7\), and \(c = 1\). Substitute these values into the formula: \[x = \frac{-(-7) \pm \sqrt{(-7)^2 - 4 \cdot 11 \cdot 1}}{2 \cdot 11}\].
03
Calculate the Discriminant
Calculate the discriminant \(b^2 - 4ac\), which will help us identify the nature of the roots: \((-7)^2 - 4 \times 11 \times 1 = 49 - 44 = 5\). As the discriminant is positive, the equation has two distinct real solutions.
04
Solve for the Roots
Now substitute the discriminant back into the quadratic formula: \[x = \frac{7 \pm \sqrt{5}}{22}\]. This gives us two solutions: \[x = \frac{7 + \sqrt{5}}{22}\] and \[x = \frac{7 - \sqrt{5}}{22}\].
05
Graphical Representation
To graphically represent the solutions, draw the parabola \(y = 11x^2 - 7x + 1\) and the line \(y = 0\). The x-coordinates where the parabola intersects the x-axis represent the solutions: \(x = \frac{7 + \sqrt{5}}{22}\) and \(x = \frac{7 - \sqrt{5}}{22}\). Use graphing software or a calculator to aid with the graph.
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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 to solve quadratic equations of the form \(ax^{2} + bx + c = 0\). It provides a straightforward method to find the values of \(x\) that satisfy this equation. The formula is given by:
\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]
Using this formula saves time and reduces error, especially with complex fractions and roots.
Remembering each component:
\[x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}\]
Using this formula saves time and reduces error, especially with complex fractions and roots.
Remembering each component:
- \(a\), \(b\), and \(c\) are coefficients from the equation \(ax^2 + bx + c\)
- \(-b\) indicates the change in sign of the coefficient \(b\)
- \(\pm\) denotes that there are usually two solutions: one by adding, the other by subtracting
Discriminant
The discriminant in the quadratic formula is the part under the square root, \(b^2 - 4ac\). It plays a crucial role in determining the nature of the roots of the quadratic equation.
The value of the discriminant can tell us the following:
The value of the discriminant can tell us the following:
- If it is positive, the equation has two distinct real solutions.
- If it is zero, the quadratic has exactly one real solution, or a repeated root.
- If negative, there are no real solutions, only complex or imaginary solutions.
Graphical Solution
Graphical solutions provide a visual interpretation of where the solutions to a quadratic equation lie. This involves plotting the quadratic function as a parabola on the graph, such as \(y = 11x^2 - 7x + 1\) from the exercise.
Follow these steps for a graphical solution:
Follow these steps for a graphical solution:
- Set up your graph with appropriate scales for \(x\) and \(y\).
- Graph the quadratic equation, recognizing that the parabola opens upwards as the coefficient of \(x^2\) (\(11\)) is positive.
- Identify where the parabola intersects the \(x\)-axis. These intersection points represent where \(y = 0\), or the solutions of the quadratic equation.