Chapter 1: Problem 45
Find an expression for the function whose graph is the given curve. The bottom half of the parabola \(x+(y-1)^{2}=0\)
Short Answer
Expert verified
The function is \( y = 1 - \sqrt{-x} \).
Step by step solution
01
Identify the given equation
We start by examining the given equation, which is a parabola: \[ x + (y - 1)^2 = 0 \]This equation represents a parabola that opens horizontally rather than vertically.
02
Solve for y
To express the given equation as a function of \(x\), we solve for \(y\):\[ (y - 1)^2 = -x \] Taking the square root of both sides, we obtain:\[ y - 1 = \pm \sqrt{-x} \]Thus, \[ y = 1 \pm \sqrt{-x} \]
03
Determine the correct branch
Since we are tasked with finding the bottom half of the parabola, we select the negative branch of the square root:\[ y = 1 - \sqrt{-x} \] This function represents the bottom half of the parabola because it decreases as \(x\) moves leftward (decreasing).
04
Verify the function
Substitute back into the original equation to verify: \[ x + ((1 - \sqrt{-x}) - 1)^2 = 0 \] Simplifying, \[ x + (-\sqrt{-x})^2 = 0 \] \[ x + (-x) = 0 \] which is true. Thus, the function \(y = 1 - \sqrt{-x}\) correctly describes the bottom half of the parabola.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Exploring the Function of x
When we talk about a function of x, we are referring to a type of mathematical relationship. This relationship involves an equation where the value of the variable y is determined based on the input x.
Understanding that we have a function of x helps us recognize which y-coordinates the parabola will cover as x values change.
- An equation like this, characterized by y being expressed in terms of x, is called a function.
- The notation often used for functions is f(x), meaning the function dependent on x, or it can simply be written as y.
Understanding that we have a function of x helps us recognize which y-coordinates the parabola will cover as x values change.
Mastering Solving Quadratic Equations
Solving quadratic equations is a fundamental skill in algebra, useful for various applications such as finding the roots of a polynomial or expressing a parabola in standard terms.
Quadratic equations generally have the form \(ax^2 + bx + c = 0\). In this exercise though, we encounter an unconventional parabola equation, \(x + (y - 1)^2 = 0\).
Quadratic equations generally have the form \(ax^2 + bx + c = 0\). In this exercise though, we encounter an unconventional parabola equation, \(x + (y - 1)^2 = 0\).
- To solve this, especially for a function of one variable, we perform algebraic manipulations to isolate the variable of interest, y in this case.
- This involves rearranging terms and, as evidenced here, sometimes taking square roots to simplify to \(y = 1 \pm \sqrt{-x}\).
Understanding Horizontal Parabolas
Typically, parabolas are vertical, opening up or down along the y-axis. However, horizontal parabolas flip this standard orientation, opening left or right along the x-axis.
The equation \(x + (y - 1)^2 = 0\) describes such a horizontal parabola. Here, instead of x being dependent on y, the role is reversed, making the traditional vertex form more focused on the y variable.
The equation \(x + (y - 1)^2 = 0\) describes such a horizontal parabola. Here, instead of x being dependent on y, the role is reversed, making the traditional vertex form more focused on the y variable.
- Horizontal parabolas are indicated by the squared term being associated with y (as in \((y-1)^2\)), unlike vertical ones where x is squared.
- In this exercise, the equation shows the parabola opening to the left rather than the right. This is due to a negative x term resulting from solving \((y - 1)^2 = -x\).