Chapter 10: Problem 36
Find an equation of the parabola that satisfies the given conditions. Vertex \(V(3,-2),\) axis parallel to the \(x\) -axis, and \(y\) -intercept 1
Short Answer
Expert verified
The equation of the parabola is \((y + 2)^2 = -3(x - 3)\).
Step by step solution
01
Understand the Parabola Structure
Since the parabola has a vertex at \(V(3, -2)\) and its axis is parallel to the \(x\)-axis, it is horizontally oriented. The general equation for a horizontally oriented parabola with vertex \((h, k)\) is \((y - k)^2 = 4p(x - h)\). For our parabola, \(h = 3\) and \(k = -2\). Substitute these into the equation.
02
Substitute Known Values into the General Equation
Plug the vertex values \(h = 3\) and \(k = -2\) into the equation \((y - k)^2 = 4p(x - h)\). This gives us: \[(y + 2)^2 = 4p(x - 3)\]
03
Use the Given y-Intercept to Find p
We know that the parabola crosses the \(y\)-axis at \(y = 1\), when \(x = 0\). Substitute \((x, y) = (0, 1)\) into the equation \((y + 2)^2 = 4p(x - 3)\). \[(1 + 2)^2 = 4p(0 - 3)\]Simplifying, this gives us: \[9 = -12p\]
04
Solve for p
Continue from the equation \(9 = -12p\) to find \(p\). Solve for \(p\) by dividing both sides by \(-12\):\[p = -\frac{3}{4}\]
05
Write the Final Equation of the Parabola
Now that we have \(p = -\frac{3}{4}\), substitute it back into the equation \((y + 2)^2 = 4p(x - 3)\):\[(y + 2)^2 = 4\left(-\frac{3}{4}\right)(x - 3)\]Simplify to get the final equation:\[(y + 2)^2 = -3(x - 3)\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Vertex Form
The vertex form of a parabola equation is essential for designing and manipulating parabolas easily. It generally looks like this for a horizontally oriented parabola:
The parameters \(h\) and \(k\) essentially "shift" the parabola left/right and up/down, respectively. This makes the vertex form a powerful tool in graphing parabolas.
- \((y - k)^2 = 4p(x - h)\)
- \((h, k)\),
The parameters \(h\) and \(k\) essentially "shift" the parabola left/right and up/down, respectively. This makes the vertex form a powerful tool in graphing parabolas.
Horizontally Oriented Parabola
A horizontally oriented parabola differs from the more familiar vertically oriented parabola in that it opens to the left or right instead of up or down.
- The axis of symmetry for this type is parallel to the \(x\)-axis.
- \((y - k)^2 = 4p(x - h)\)
Y-Intercept
The \(y\)-intercept of a graph is the point where it crosses the \(y\)-axis. This is expressed as \((0, c)\). It is an important property because it represents a specific relationship between the variables in the equation.
When given the \(y\)-intercept, you can substitute \(y\) and \(x\) with these values in the equation to solve for unknown constants like \(p\). In this exercise, our intercept \((0, 1)\) means when \(x = 0\), \(y = 1\).
This helps in confirming portions of your equation are handled correctly. In the derived equation
When given the \(y\)-intercept, you can substitute \(y\) and \(x\) with these values in the equation to solve for unknown constants like \(p\). In this exercise, our intercept \((0, 1)\) means when \(x = 0\), \(y = 1\).
This helps in confirming portions of your equation are handled correctly. In the derived equation
- \((y + 2)^2 = 4p(x - 3)\),
Solving for P
In a horizontally oriented parabola, the variable \(p\) represents a parameter determining the "width" and "direction" of the parabola. To solve for \(p\), we rely on given conditions, such as intercepts or specific graph points.
Therefore, \(p = -\frac{3}{4}\), determining the degree and direction of the parabola's "openness." This is crucial for completing the equation
- With a \(y\)-intercept, you can substitute known values into your equation to solve for \(p\).
- \((y + 2)^2 = 4p(x - 3)\),
- \(9 = -12p\).
Therefore, \(p = -\frac{3}{4}\), determining the degree and direction of the parabola's "openness." This is crucial for completing the equation
- \((y + 2)^2 = -3(x - 3)\),