Multivariable Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 0-53849-787-4
ISBN 13: 978-0-53849-787-9

Chapter 10 - Parametric Equations and Polar Coordinates - Review - True-False Quiz - Page 709: 9

Answer

TRUE

Work Step by Step

By rotating and translating the parabola, we can assume that it has an equation of the form $y=cx^{2}$ where $c>0$. The tangent at the point $(a,ca^{2})$ is the line $y-ca^{2}=2ca(x-a)y$ $=2cax-ca^{2}$ The tangent meets the parabola at the points $(x,cx^{2})$ where $cx^{2}=2cax-ca^{2}$ Thus, $x^{2}=2ax-a^{2}$ $x^{2}-2ax+a^{2}=0$ $(x-a)^{2}=0$ This implies $x=a$ Therefore, the tangent meets the parabola at the points $(a,ca^{2})$ at exactly one point. Hence, the given statement is true.
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