Chapter 8: Problem 51
Use a system of equations to find the parabola of the form \(y=a x^{2}+b x+c\) that goes through the three given points. $$(0,0),(1,3),(2,2)$$
Short Answer
Expert verified
The equation of the parabola is \(y = -2x^2 + 5x\).
Step by step solution
01
Set Up the Equations
Use the general form of a parabola, \(y = ax^2 + bx + c\). Substitute each given point into the equation to create a system of three equations. For point \((0,0)\): \(0 = a(0)^2 + b(0) + c\), which simplifies to \(c = 0\). For point \((1,3)\): \(3 = a(1)^2 + b(1) + c\), which simplifies to \(3 = a + b + c\). For point \((2,2)\): \(2 = a(2)^2 + b(2) + c\), which simplifies to \(2 = 4a + 2b + c\).
02
Substitute Known Values
From Step 1, we know \(c = 0\). Substitute \(c = 0\) into the remaining equations: \(3 = a + b\) and \(2 = 4a + 2b\).
03
Solve the System of Equations
We now have two equations with two variables: \(3 = a + b\) and \(2 = 4a + 2b\). Solve the first equation for one variable: \(b = 3 - a\). Substitute this into the second equation: \(2 = 4a + 2(3 - a)\). Simplify and solve for \(a\): \(2 = 4a + 6 - 2a\) or \(2 = 2a + 6\) or \(-4 = 2a\) or \(a = -2\).
04
Find Remaining Variable
Substitute \(a = -2\) back into \(b = 3 - a\): \(b = 3 - (-2)\) or \(b = 5\).
05
Write the Parabola Equation
Combine the values of \(a\), \(b\), and \(c\) into the general form \(y = ax^2 + bx + c\). Therefore, the equation of the parabola is \(y = -2x^2 + 5x\).
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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 can open upwards or downwards. It is the graph of a quadratic function. The most basic form of a parabola opens upwards and is symmetrical around a vertical axis of symmetry. When graphed on a coordinate plane, it generally looks like a bowl or a hill, depending on its concavity.
Parabolas have several key features:
Parabolas have several key features:
- **Vertex**: The highest or lowest point of the parabola, also the point where the axis of symmetry intersects the parabola.
- **Axis of Symmetry**: The vertical line that splits the parabola into two mirror-image halves.
- **Focus and Directrix**: Geometric traits used to define the parabola. The distance from any point on the parabola to the focus equals the distance from that point to the directrix.
- If 'a' is positive, the parabola opens upwards.
- If 'a' is negative, it opens downwards.
- The values of 'b' and 'c' affect the position of the vertex and the parabola's intersection with the y-axis.
quadratic functions
Quadratic functions are fundamental in algebra and feature prominently in many real-life scenarios. They can be used to model phenomena such as projectile motion, profit maximization in business, and many more. The standard form of a quadratic function is: \(y = ax^2 + bx + c\)
Let's delve into the details:
Let's delve into the details:
- **Coefficient 'a'**: Determines the
systems of linear equations
To find the equation of a parabola passing through three points, we must use systems of linear equations. This might sound complicated, but it's manageable with a few steps.
Any quadratic function can be expressed as: \(y = ax^2 + bx + c\).
Suppose you have three points given, say \((x_1, y_1)\), \((x_2, y_2)\), and \((x_3, y_3)\). To find the quadratic equation, substitute these points into the quadratic function:
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Any quadratic function can be expressed as: \(y = ax^2 + bx + c\).
Suppose you have three points given, say \((x_1, y_1)\), \((x_2, y_2)\), and \((x_3, y_3)\). To find the quadratic equation, substitute these points into the quadratic function:
- For \((x_1, y_1)\): \(y_1 = a x_1^2 + b x_1 + c\).