Mathematics

Problem

If the derivative of a differentiable function

f

is decreasing on an open interval, which of the following must be true on that interval? a)

f\,\text{is concave up.}

f\,\text{is increasing.}

f\,\text{is concave down.}

f\,\text{has an inflection point at every } x \,\text{in the interval.}