MATHEMATICS · Single correct · AP · Calculus AB · Differentiation: Composite, Implicit, and Inverse Functions · Differentiation: Composite, Implicit, and Inverse Functions
Problem
For the composite function y = f(g(x)), suppose that at x = 4 the following are true:
• g′(4)<0
• f′(g(4))<0
Which statement best describes the behavior of y near x = 4?
(a) y is decreasing because dxdy<0
(b) y is increasing because dxdy>0
(c) y has a horizontal tangent because dxdy=0
(d) The behavior cannot be determined without knowing the magnitudes of g′(4) and f′(g(4))