Mathematics

Problem

Which of the following best describes the concavity of the curve

x^{2}+y^{2}-4y=0

at the point

(0,0)

? a) Concave down, since

\displaystyle \frac{d^{2}y}{dx^{2}}<0

. b) Indeterminate, because

\displaystyle \frac{dy}{dx}

is undefined at

(0,0)

. c) Concave up, since

\displaystyle \frac{d^{2}y}{dx^{2}}>0

. d) An inflection point, since

\displaystyle \frac{d^{2}y}{dx^{2}}=0