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The function f(x) = (x-1)³(x+4) has a zero at x=1. What is the behavior of the graph of f at this zero?

The function f(x)=(x−1)3(x+4)f(x) = (x-1)^3(x+4) has a zero at x=1x=1. What is the behavior of the graph of ff at this zero?

Answer and explanation

Answer: A: The graph crosses the x-axis at x=1.

The factor (x−1)3(x - 1)^3 has odd multiplicity, 3, at the zero x=1x = 1. Zeros of odd multiplicity are crossings: the graph passes through the xx-axis, flattening out near the zero because of the multiplicity 3. That makes A correct. Choice B describes even multiplicity, as in (x−1)2(x-1)^2, where the graph touches and turns back. Choice C is wrong, because a vertical asymptote needs a factor in the denominator and this function is a polynomial. Choice D is wrong because f(1)=0f(1) = 0 is defined; polynomials are defined for every real number.

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