Which of the following functions is continuous at every real number?

MATHEMATICS · Single correct · AP · Calculus AB · Limits and Continuity · Limits and Continuity

Problem

Which of the following functions is continuous at every real number? (a)

k(x)=\sqrt{x}

(b)

f(x)=3x^{4}-2x+7

(c)

p(x)=\dfrac{x^{2}-4}{x-2}

(d)

h(x)=\begin{cases}1,& x<0\\2,& x\ge 0\end{cases}