Chapter 9: Problem 34
Represent the solution graphically. Check the solution algebraically. $$ x^{2}+2 x=3 $$
Short Answer
Expert verified
The solutions of the equation are x = 1 and x = -3
Step by step solution
01
Rearrange the equation
First, simplify the equation by moving the constant term to one side. So the equation becomes, \(x^{2} + 2x - 3 = 0\)
02
Plot the function
The function corresponding to the equation is \(y = x^{2} + 2x - 3\). By plotting this function, you will get a parabola and can read its roots from the graph, which are the x-values where the function intersects the x-axis.
03
Solve for x using the quadratic formula
The quadratic formula is given by \(-\frac{b}{2a} \pm \frac{\sqrt{b^2-4ac}}{2a}\), where a, b and c are coefficients of the quadratic equation. In this case, a = 1, b = 2 and c = -3. Substituting these values into the formula, you find that the solutions are \(x = 1\) and \(x = -3\)
04
Check the solution algebraically
Substitute the solution back into the original equation to verify. For \(x = 1\), \(1^2 + 2*1 = 3\), which is true. For \(x = -3\), \((-3)^2 + 2*-3 = 3\), which is also true. So, the roots are correct
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Parabola
A parabola is a U-shaped curve that appears in the graph of a quadratic equation like the one given in the exercise: \(y = x^2 + 2x - 3\).
Whenever you plot a quadratic equation, you will see this characteristic shape. The highest or the lowest point of a parabola is called the "vertex." In this particular equation, the parabola opens upwards because the coefficient of \(x^2\) is positive.
Some important features of a parabola include:
Whenever you plot a quadratic equation, you will see this characteristic shape. The highest or the lowest point of a parabola is called the "vertex." In this particular equation, the parabola opens upwards because the coefficient of \(x^2\) is positive.
Some important features of a parabola include:
- Axis of Symmetry: A vertical line that divides the parabola into two mirror-image halves. In our equation, the axis of symmetry can be found using the formula \(x = -\frac{b}{2a}\).
- Vertex: The turning point of the parabola, found at the axis of symmetry. For our function, it's located at \((-1, -4)\).
- Intercepts: The points where the parabola cuts the axes. The x-intercepts are the solutions to the equation, which we'll find using the quadratic formula. There's also a y-intercept at \(y = -3\), where the parabola crosses the y-axis.
Quadratic Formula
The quadratic formula is a universal tool for solving quadratic equations like \(x^2 + 2x - 3 = 0\).
When factoring doesn't work or isn't obvious, the quadratic formula comes to the rescue. It is given by:
\[x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}\]where \(a\), \(b\), and \(c\) are the coefficients in the quadratic equation \(ax^2 + bx + c = 0\).
When factoring doesn't work or isn't obvious, the quadratic formula comes to the rescue. It is given by:
\[x = \frac{-b \pm \sqrt{b^2-4ac}}{2a}\]where \(a\), \(b\), and \(c\) are the coefficients in the quadratic equation \(ax^2 + bx + c = 0\).
- In our exercise, identify the coefficients: \(a = 1\), \(b = 2\), and \(c = -3\).
- Substitute these values into the formula to find the roots of the equation.
- This formula efficiently finds real or complex roots depending on the discriminant \(b^2 - 4ac\). If the discriminant is positive, you get two real roots. If it's zero, there is one real root. A negative discriminant indicates complex roots.
Roots of Equations
Finding the roots of a quadratic equation means determining the values of \(x\) that make the equation true—essentially, where it touches or crosses the x-axis in the graph.
These x-values are also known as the "solutions" or "zeros" of the equation. In our quadratic equation \(x^2 + 2x - 3 = 0\), we found the roots by plotting the parabola and using the quadratic formula.
These x-values are also known as the "solutions" or "zeros" of the equation. In our quadratic equation \(x^2 + 2x - 3 = 0\), we found the roots by plotting the parabola and using the quadratic formula.
- Double-checking with a graph: Graphing the equation and observing where the parabola intersects the x-axis can visually confirm the roots, which can be seen at \(x = 1\) and \(x = -3\).
- Verification: Substitute the roots back into the original equation to ensure the solution satisfies it. If substituting \(x = 1\) and \(x = -3\) results in a true equation, the solutions are correctly identified.
- Real-life applications: Understanding roots is essential for solving real-world problems, such as physics equations describing motion, economics models, or any scenario where predicting outcomes is important.