Let and . The curve is concave downward when . Which one of the following values of…

MATHEMATICS · Single correct · CBSE · Mathematics · Continuity and Differentiability · Continuity and Differentiability

Problem

Let

x=t^{3}

and

y=t^{2}-4t

. The curve is concave downward when

\dfrac{d^{2}y}{dx^{2}}<0

. Which one of the following values of

t

satisfies this condition? (a)

4

(b)

-2

(c)

1

(d)

2