A point moves along the ellipse

MATHEMATICS · Single correct · AP · Calculus AB · Contextual Applications of Differentiation · Contextual Applications of Differentiation

Problem

4x^{2}+y^{2}=20

. At an instant when the point is in the first quadrant (

x>0,\,y>0

) its

x

–coordinate is decreasing at a rate of

3\text{ cm/s}

. Which statement about the instantaneous rate of change of the

y

–coordinate is true? (a)

\dfrac{dy}{dt}=0

(b)

\dfrac{dy}{dt}

is negative (c)

\dfrac{dy}{dt}

is positive (d) The sign of

\dfrac{dy}{dt}

cannot be determined from the given information