/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 7 If \(x^{2}+y^{2}=25\) and \(d x ... [FREE SOLUTION] | 91Ó°ÊÓ

91Ó°ÊÓ

If \(x^{2}+y^{2}=25\) and \(d x / d t=-2,\) then what is \(d y / d t\) when \(x=3\) and \(y=-4 ?\)

Short Answer

Expert verified
\(\frac{dy}{dt} = \frac{3}{2}\).

Step by step solution

01

Understand the Problem

We are given a circle equation \(x^2 + y^2 = 25\), representing a circle with a radius of 5. We need to find the rate at which \(y\) changes over time \( \left( \frac{dy}{dt} \right) \), given that \( \frac{dx}{dt} = -2 \), when \(x = 3\) and \(y = -4\).
02

Differentiate the Equation with Respect to Time

Differentiate both sides of the equation \(x^2 + y^2 = 25\) with respect to \(t\). This gives: \(2x \frac{dx}{dt} + 2y \frac{dy}{dt} = 0\).
03

Substitute Known Values

Substitute \(x = 3\), \(y = -4\), and \(\frac{dx}{dt} = -2\) into the differentiated equation: \(2(3)(-2) + 2(-4) \frac{dy}{dt} = 0\).
04

Simplify the Equation

Simplify the equation: \(-12 - 8 \frac{dy}{dt} = 0\).
05

Solve for \(\frac{dy}{dt}\)

Rearrange the equation to solve for \(\frac{dy}{dt}\): \(-8 \frac{dy}{dt} = 12\), which simplifies to \(\frac{dy}{dt} = -\frac{12}{-8} = \frac{3}{2}\).

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with 91Ó°ÊÓ!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Implicit Differentiation
In calculus, implicit differentiation is a technique used to differentiate equations where the variables are not easily separated. This approach is particularly useful when dealing with equations that define a relationship between two or more variables. Instead of isolating one variable on one side, we differentiate each term with respect to time or another variable.
  • Let's consider the equation of a circle: \(x^2 + y^2 = 25\). Both \(x\) and \(y\) are related through this equation.
  • To find the rate of change of \(y\) with respect to time, \(\frac{dy}{dt}\), we apply implicit differentiation.
When differentiating the circle's equation with respect to time, remember that both \(x\) and \(y\) are changing over time. This leads us to differentiate each of these terms as a function of \(t\). Using the power rule and chain rule, we get: \[ 2x \frac{dx}{dt} + 2y \frac{dy}{dt} = 0 \] This equation encapsulates how both \(x\) and \(y\) change together over time.
Circle Equations
Circle equations, such as \(x^2 + y^2 = r^2\), describe geometric shapes where any point \((x, y)\) is at a constant distance \(r\) (the radius) from the center of the circle. In this exercise, the equation \(x^2 + y^2 = 25\) represents a circle centered at the origin \((0,0)\) with a radius of 5.

  • The power of circle equations comes from how they geometrically bind two variables. Here, \(x\) and \(y\) remain fixed at a consistent distance of 5 from the center.
  • This constraint is crucial when determining rates of change since any alteration in one variable must induce a change in the other to maintain the equation's balance.
Understanding these relationships helps when solving related rates problems, as changes in one variable will typically affect others while maintaining the geometric harmony represented by the equation.
Calculus Problems
Calculus problems often involve analyzing how quantities change with respect to one another. When tackling these challenges, it's important to identify what you're looking for and what is given. In this problem, we focus on finding \(\frac{dy}{dt}\) given the rate \(\frac{dx}{dt}\) and certain values of \(x\) and \(y\).
  • Start by clearly understanding how the variables interact, in this case through the circle's equation.
  • Differentiating the equation implicitly allows us to link the rates of change of \(x\) and \(y\) with respect to time.
  • This leads to an equation involving \(\frac{dx}{dt}\) and \(\frac{dy}{dt}\), which can be solved using the given values for \(x\), \(y\), and \(\frac{dx}{dt}\).
In real-world applications, related rates problems help model everything from physics problems to economic trends, where understanding one rate can provide insight into another. Breaking down and simplifying the problem is key to uncovering the needed solutions.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

Graph \(y=3 x^{2}\) in a window that has \(-2 \leq x \leq 2,0 \leq y \leq 3\) Then, on the same screen, graph $$y=\frac{(x+h)^{3}-x^{3}}{h}$$ for \(h=2,1,0.2 .\) Then try \(h=-2,-1,-0.2 .\) Explain what is going on.

Graph \(y=1 /(2 \sqrt{x})\) in a window that has \(0 \leq x \leq 2 .\) Then, on the same screen, graph $$y=\frac{\sqrt{x+h}-\sqrt{x}}{h}$$ for \(h=1,0.5,0.1 .\) Then try \(h=-1,-0.5,-0.1 .\) Explain what is going on.

Find both \(d y / d x\) (treating \(y\) as a differentiable function of \(x\) ) and \(d x / d y\) (treating \(x\) as a differentiable function of \(y )\) . How do \(d y / d x\) and \(d x / d y\) seem to be related? Explain the relationship geometrically in terms of the graphs. \begin{equation} x^{3}+y^{2}=\sin ^{2} y \end{equation}

In Exercises \(57-60,\) use a CAS to estimate the magnitude of the error in using the linearization in place of the function over a specified interval I. Perform the following steps: $$ \begin{array}{l}{\text { a. Plot the function } f \text { over } I} \\ {\text { b. Find the linearization } L \text { of the function at the point } a \text { . }} \\ {\text { c. Plot } f \text { and } L \text { together on a single graph. }} \\ {\text { d. Plot the absolute error }|f(x)-L(x)| \text { over } I \text { and find its max- }} \\ {\text { imum value. }}\end{array} $$ $$ \begin{array}{l}{\text { e. From your graph in part (d), estimate as large a } \delta>0 \text { as you }} \\ {\text { can, satisfing }}\end{array} $$ $$ \begin{array}{c}{|x-a|<\delta \quad \Rightarrow \quad|f(x)-L(x)|<\epsilon} \\\ {\text { for } \epsilon=0.5,0.1, \text { and } 0.01 . \text { Then check graphically to see if }} \\ {\text { your } \delta \text { -estimate holds true. }}\end{array} $$ $$ f(x)=x^{3}+x^{2}-2 x, \quad[-1,2], \quad a=1 $$

A cube's surface area increases at the rate of 72 \(\mathrm{in}^{2} / \mathrm{sec} .\) At what rate is the cube's volume changing when the edge length is \(x=3\) in?

See all solutions

Recommended explanations on Math Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.