Let be differentiable on and suppose for every in this interval

MATHEMATICS · Single correct · A Level · Mathematics · Differentiation · Differentiation

Problem

Let

f

be differentiable on

(2,7)

and suppose

f'(x)<0

for every

x

in this interval. Which statement is necessarily true about

f

(2,7)

? (a)

f

has a local minimum somewhere on

(2,7)

. (b)

f

is concave down on

(2,7)

. (c)

f

is decreasing on

(2,7)

. (d)

f

is increasing on

(2,7)