Free response · Unit 3, Unit 4 Beta

A tilted oval: tangent lines and a moving point

Implicit differentiation and related rates · Part B: no calculator · 9 points

The question

Name: ______________________   Date: ____________   A tilted oval: tangent lines and a moving point (9 points)

Graph

The curve x2−xy+y2+2x−yx^2 - xy + y^2 + 2x - y=2= 2

Consider the curve given by x2−xy+y2+2x−yx^2 - xy + y^2 + 2x - y=2= 2, shown in the graph.
−3−2−11−3−2−1123xy(0, -1)(1, 1)
  1. (a) Show that dydx\frac{dy}{dx}=y−2x−22y−x−1= \frac{y - 2x - 2}{2y - x - 1}. [2 points]

  2. (b) Write an equation for the line tangent to the curve at the point (0,−1)(0, -1). [1 point]

  3. (c) Find the coordinates of all points on the curve at which the line tangent to the curve is horizontal. [3 points]

  4. (d) A particle moves along the curve. At the instant the particle passes through the point (1,1)(1, 1), dydt=3\frac{dy}{dt} = 3. Find dxdt\frac{dx}{dt} at that instant. Explain what your answer shows about the tangent line at (1,1)(1, 1). [3 points]