Thomas' Calculus 13th Edition

Published by Pearson
ISBN 10: 0-32187-896-5
ISBN 13: 978-0-32187-896-0

Chapter 3: Derivatives - Section 3.7 - Implicit Differentiation - Exercises 3.7 - Page 155: 6

Answer

$dy/dx=\frac{-18xy^2-42y}{18x^2y+42x-6}$

Work Step by Step

Take the derivative of the equation on each side separately. Apply chain rule when differentiating the "y" variables since we are differentiating with respect to x: $2(3xy+7)\times(3x\times\frac{dy}{dx}+3y)=6\times\frac{dy}{dx}$ $(6xy+14)(3x\times\frac{dy}{dx}+3y)=6\times\frac{dy}{dx}$ $18x^2y(dy/dx)+42x(dy/dx)+18xy^2+42y=6(dy/dx)$ Move all terms with dy/dx to one side of the equation, and isolate dy/dx: $18x^2y(dy/dx)+42x(dy/dx)-6(dy/dx)=-18xy^2-42y$ $dy/dx=\frac{-18xy^2-42y}{18x^2y+42x-6}$
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