OG详解-OG8 数学1 Q15

Choice C is correct. If a value of x satisfies f(x)= 0, the graph of y= f(x) will contain a point (x, 0) and thus touch the x-axis. Since there are 3 points at which this graph touches the x-axis, there are 3 values of x for which f(x)= 0.
Choice A is incorrect and may result from conceptual or calculation errors. Choice B is incorrect and may result from conceptual or calculation errors. Choice D is incorrect and may result from conceptual or calculation errors.