Chapter 1: Problem 21
Graph the equation \(4 x^{2}+2 y^{2}=1\) by solving for \(y\) and graphing two equations corresponding to the negative and positive square roots. (This graph is called an ellipse.)
Short Answer
Expert verified
Graph \(y = \pm \sqrt{\frac{1 - 4x^2}{2}}\) to form an ellipse.
Step by step solution
01
Recognize the Standard Form of an Ellipse
The given equation \(4x^2 + 2y^2 = 1\) is in the form of an ellipse equation. An ellipse generally comes in the form \(\frac{x^2}{a^2} + \frac{y^2}{b^2} = 1\). Here, we need to manipulate the given equation into this form to solve for \(y\).
02
Rearrange the Equation
We start by isolating the \(y^2\) term. Divide every term in the equation \(4x^2 + 2y^2 = 1\) by 1 to make the right side equal to 1: \[\frac{4x^2}{1} + \frac{2y^2}{1} = 1\] This is the equation of an ellipse with modifications.
03
Solve for \(y^2\)
Isolate \(y^2\) by moving \(4x^2\) to the other side: \[2y^2 = 1 - 4x^2\] Now, solve for \(y^2\) by dividing through by 2:\[y^2 = \frac{1 - 4x^2}{2}\]
04
Solve for \(y\)
Take the square root of both sides to solve for \(y\). Remember to consider both the positive and negative square roots:\[y = \pm \sqrt{\frac{1 - 4x^2}{2}}\]This gives us two equations: \(y = \sqrt{\frac{1 - 4x^2}{2}}\) and \(y = -\sqrt{\frac{1 - 4x^2}{2}}\).
05
Graph the Equations
Graph \(y = \sqrt{\frac{1 - 4x^2}{2}}\) for the top half of the ellipse, and \(y = -\sqrt{\frac{1 - 4x^2}{2}}\) for the bottom half of the ellipse. You can use a graphing calculator or software to plot these two functions and observe the complete ellipse.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Standard Form of an Ellipse
An ellipse is a fascinating shape in geometry that resembles a flattened circle. Its standard form helps us understand and describe the ellipse mathematically. Generally, an ellipse is represented by the equation:
- \[ \frac{x^2}{a^2} + \frac{y^2}{b^2} = 1 \]
- \(a^2\) is associated with the \(x\)-axis, and \(b^2\) is associated with the \(y\)-axis.
- The values of \(a\) and \(b\) depict the semi-major and semi-minor axes, respectively.
Solving for y in Equations
When you have an equation involving \(y\), sometimes it's necessary to solve for \(y\) to understand or graph the function. Our equation \(4x^2 + 2y^2 = 1\) requires us to isolate \(y\).^2. Initially, rearrange it to focus on the \(y^2\)-term:
- Subtract \(4x^2\) from both sides: \(2y^2 = 1 - 4x^2\).
- Divide everything by 2 to solve for \(y^2\): \(y^2 = \frac{1 - 4x^2}{2}\).
- The square root introduces a \(\pm\) symbol, representing both positive and negative roots.
- This means we have two expressions for \(y\): \(y = \pm \sqrt{\frac{1 - 4x^2}{2}}\).
Graphing Equations
Graphing an equation involves plotting points or lines on a coordinate plane to visually represent the relationship between variables. In the case of an ellipse, once you have the functions derived from the equation \(4x^2 + 2y^2 = 1\), you can graph them to see the ellipse's shape.To graph the ellipse, follow these steps:
- Use the equations \(y = \sqrt{\frac{1 - 4x^2}{2}}\) for the top half and \(y = -\sqrt{\frac{1 - 4x^2}{2}}\) for the bottom half.
- Make a table of values for \(x\), calculating the corresponding \(y\) values for each equation.
- Plot these points on a graph to visualize the halves forming a complete ellipse.
- You can use graphing software or calculators to make this process easier and more accurate.