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Advanced Math / Nonlinear functions Difficulty: Hard
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The graph of y=f(x)y=fx is shown, where f(x)=abx+cfx=abx+c, and aa , bb , and cc are constants. For how many values of xx does f(x)=0fx=0?

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Explanation

Choice D is correct. Each point (x,y)x,y on the graph of y=f(x)y=f(x) in the xy-plane gives a value of xx and its corresponding value of f(x)f(x), or yy. For any value of xx for which f(x)=0f(x)=0, there is a corresponding point on the graph of y=f(x)y=f(x) with a y-coordinate of 00. A point with a y-coordinate of 00 is a point where the graph intersects the x-axis. It's given that f(x)=abx+cfx=abx+c, where aa, bb, and cc are constants. In the xy-plane, the graph of an equation of this form will lie entirely either above or below the horizontal line defined by y=cy=c. The part of the graph of y=f(x)y=f(x) shown lies entirely below the horizontal line defined by y=7y=-7, and thus the entire graph of y=f(x)y=f(x) must lie below the line defined by y=7y=-7. It follows that the graph of y=f(x)y=f(x) will never intersect the x-axis. Therefore, there are zero values of x for which f(x)=0f(x)=0.

Choice A is incorrect and may result from conceptual errors.

Choice B is incorrect and may result from conceptual errors.

Choice C is incorrect and may result from conceptual errors.