Chapter 2: Problem 18
Find a single function defined implicitly by the given equation. Graph the function and give its domain. Use a graphing utility if necessary.] $$ -x+\sqrt{y}+2=0 $$
Short Answer
Expert verified
The function defined is \(y = (x - 2)^2\), with domain \(x \in \mathbb{R}\).
Step by step solution
01
Solve for y in Terms of x
Rearrange the given implicit equation \(-x + \sqrt{y} + 2 = 0\) to solve for \(y\). Start by isolating \(\sqrt{y}\) on one side: \[\sqrt{y} = x - 2\]. Now, square both sides to solve for \(y\): \[y = (x - 2)^2\]. This is the explicit function in terms of \(x\).
02
Define the Domain
The expression \((x - 2)^2\) is defined for all real numbers because any real number squared gives a non-negative result, which means \(y\) can take any non-negative value. However, since the square root \(\sqrt{y}\) in the implicit equation must have been non-negative, \(y\) must also be non-negative. Thus, the explicit function \(y = (x-2)^2\) is valid for all real \(x\). The domain of \(y = (x - 2)^2\) is all real numbers, \(x \in \mathbb{R}\).
03
Graph the Function
Graph the function \(y = (x - 2)^2\). This is a parabola opening upwards with its vertex located at the point \((2, 0)\). This graph illustrates all points \((x, y)\) satisfying the equation, showing that any real \(x\) results in a valid non-negative \(y\) value.
04
Use a Graphing Utility if Necessary
If a graphing calculator or computer software is available, use it to create a precise graph of the function \(y = (x-2)^2\). This can help in visualizing the parabola and verifying the domain and range conclusions.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Function Graphing
Graphing functions helps us visualize how the values change. To graph a function, you plot points in an x-y plane based on the function’s equation. For our equation, we first solve for one variable in terms of others to get an explicit function like \( y = (x-2)^2 \).
- This function is called an explicit function because \( y \) is given directly as a formula in terms of \( x \).
- Creating a graph involves plotting points derived from values you plug into the function.
Domain of a Function
Understanding the domain is crucial as it tells us all possible x-values a function can accept. For the function \( y = (x-2)^2 \), the domain is all real numbers.
- This is because there's no restriction on \( x \) in the equation; any real number plugged in results in a valid \( y \) value.
- Since the function involves squaring \((x-2)\), it naturally handles both positive and negative \( x \) values.
Solving Equations
Solving equations involves finding the values of variables that satisfy given conditions. In implicit equations, both variables are initially on the same side. For \( -x + \sqrt{y} + 2 = 0 \), we rearrange it to find an explicit expression for \( y \).
- First, isolate \( \sqrt{y} \) by adding \( x \) and subtracting 2 from both sides, yielding \( \sqrt{y} = x - 2 \).
- Next, square both sides to solve for \( y \): \( y = (x - 2)^2 \).
Parabolic Functions
Parabolic functions, like \( y = (x-2)^2 \), form a specific category of functions with distinct features.
- They graph as U-shaped curves,
- which can open upwards or downwards based on the sign of the squared term.
- Our function's parabola opens upwards, indicated by the positive coefficient of the \( (x-2)^2 \) term.
- The vertex of \( y = (x-2)^2 \) is at \((2, 0)\), showing the lowest point in this case.