Chapter 12: Problem 74
Graph each relation on a graphing calculator by solving for \(y\) and graphing two functions. $$x=4 y^{2}+4 y+1$$
Short Answer
Expert verified
The functions to graph are \(y_1 = \frac{-1 + \sqrt{x}}{2}\) and \(y_2 = \frac{-1 - \sqrt{x}}{2}\).
Step by step solution
01
Rewrite the Equation
Rewrite the equation in a standard quadratic form in terms of y. The given equation is \[ x = 4y^2 + 4y + 1\]
02
Solve for y
To graph the relation, we need to solve for y. Rewrite the equation in the form of a quadratic equation in terms of y:\[ 4y^2 + 4y + 1 - x = 0 \]This is a standard quadratic equation of the form \[ ay^2 + by + c = 0 \]where \[ a = 4, b = 4, \text{ and } c = 1 - x \]
03
Apply the Quadratic Formula
The quadratic formula is given by \( y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \).Substitute the values of a, b, and c into the quadratic formula:\[ y = \frac{-4 \pm \sqrt{4^2 - 4 \cdot 4 \cdot (1 - x)}}{2 \cdot 4} = \frac{-4 \pm \sqrt{16 - 16 + 16x}}{8} = \frac{-4 \pm \sqrt{16x}}{8} \]Further simplify to find the solutions for y:\[ y = \frac{-4 \pm 4\sqrt{x}}{8} = \frac{-4 (1 \pm \sqrt{x})}{8} = \frac{-1 \pm \sqrt{x}}{2} \]
04
Express y in Terms of x
The solutions to y in terms of x are:\[ y = \frac{-1 + \sqrt{x}}{2} \]and\[ y = \frac{-1 - \sqrt{x}}{2} \]These represent two functions: \[ y_1 = \frac{-1 + \sqrt{x}}{2} \]and\[ y_2 = \frac{-1 - \sqrt{x}}{2} \]
05
Graph Each Function
Graph the two functions obtained from solving for y. Enter these equations into a graphing calculator:\( y_1 = \frac{-1 + \sqrt{x}}{2} \)and\( y_2 = \frac{-1 - \sqrt{x}}{2} \).These will give the graph of the original relation, and the resulting graph will show both branches of the curve.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Equation
A quadratic equation is a polynomial equation of the second degree. It takes the general form \[ ax^2 + bx + c = 0 \] where * \(a, b,\) and \(c\) are constants, and * \(x\) is the variable. In this particular exercise, we have the equation \[ 4y^2 + 4y + 1 - x = 0 \] where * \(a = 4\), * \(b = 4\), and * \(c = 1 - x\).
Understanding how to manipulate and solve quadratic equations is crucial for graphing quadratic relations.
Understanding how to manipulate and solve quadratic equations is crucial for graphing quadratic relations.
Graphing Calculator
A graphing calculator is a powerful tool that helps you visualize mathematical functions. It allows you to input equations and see their graphs on a screen. For this exercise, you will input the two functions\( y_1 = \frac{-1 + \sqrt{x}}{2} \) and \( y_2 = \frac{-1 - \sqrt{x}}{2} \).
Helpful tips on using a graphing calculator:
Helpful tips on using a graphing calculator:
- Make sure you enter the equations correctly.
- Check your graph window settings to ensure it covers the relevant range for \(x\) and \(y\).
- Use the zoom features to get a clearer view of the graph.
Quadratic Formula
The quadratic formula is a key tool for solving quadratic equations. It is given by: \[ y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] where:
These solutions express \(y\) in terms of \(x\), making it easier to graph the relations.
- \(a\) is the coefficient of \(y^2\)
- \(b\) is the coefficient of \(y\)
- \(c\) is the constant term
These solutions express \(y\) in terms of \(x\), making it easier to graph the relations.
Solving for y
Solving for \(y\) means isolating \(y\) on one side of the equation to express it as a function of \(x\). Here's how it was done step-by-step in this exercise:
- First, rewrite the equation \[ x = 4y^2 + 4y + 1\] in a standard quadratic form: \[ 4y^2 + 4y + 1 - x = 0\]
- Next, use the quadratic formula \[ y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \] with \(a = 4\), \(b = 4\), and \(c = 1 - x\).
- Simplify the solutions to provide the two functions: \[ y_1 = \frac{-1 + \sqrt{x}}{2}\] and \[ y_2 = \frac{-1 - \sqrt{x}}{2}\]