Free response · Unit 7 Beta

Slope field, tangent line and separation for dy/dx = x(4 - y)

Differential equation and slope field · Part B: no calculator · 9 points

The question

Name: ______________________   Date: ____________   Slope field, tangent line and separation for dy/dx = x(4 - y) (9 points)

Graph

Nine points for the slope field of dydx=x(4−y)\frac{dy}{dx} = x(4 - y)

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  1. (a) Consider the differential equation dydx=x(4−y)\frac{dy}{dx} = x(4 - y). On the axes provided, sketch a slope field for the equation at the nine points shown. [1 point]

  2. (b) Let y=f(x)y = f(x) be the particular solution to the differential equation with f(2)=3f(2) = 3. Write an equation for the line tangent to the graph of ff at x=2x = 2, and use it to approximate f(2.1)f(2.1). [2 points]

  3. (c) Find d2ydx2\frac{d^2y}{dx^2} in terms of xx and yy. Determine whether the approximation in part (b) is an overestimate or an underestimate of f(2.1)f(2.1). Give a reason for your answer. [2 points]

  4. (d) Find y=f(x)y = f(x), the particular solution to the differential equation with the initial condition f(2)=3f(2) = 3. [4 points]