SOLUTION: Determine if the function is one-to-one by noting the function family to which it belongs and mentally picturing the shape of its graph. f (x) = –|x + 2| – 9 Select one: a.

This is an absolute value function.

The graph of a function must never pass DIRECTLY ABOVE itself or 
DIRECTLY BELOW itself.

The graph of a ONE-TO-ONE function not only must never pass DIRECTLY 
ABOVE itself or DIRECTLY BELOW itself, it also must never pass 
DIRECTLY RIGHT of itself or DIRECTLY LEFT of itself. 

The graph of a parabola (u-shaped graph) or an absolute value function
(a v-shaped graph or an upside-down v-shaped graph).  A u or v-shaped 
graph has some points that are directly left or directly right of some
other points it has, so a parabola or an absolute value function is NOT a
one-to-one function.

Edwin