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Find the zeros of f(x)=-x³-2x²+7x-4. Then describe the behavior of the graph of fat each zero.

A 4,-1, As x →-[infinity], f. When-1 1,f→-[infinity].
B 4.1, As x →-[infinity] f. When-40. At x = 1, 1 is tangent to the x-axis, so when x > 1, f → [infinity].
C. 4,-1: As x → -[infinity] f. When-1 0. At x=4, f is tangent to the x-axis, so when x>1,→ [infinity].
D. 4, 1; As x → -[infinity] f. When-41, f →-[infinity].

User Peevesy
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1 Answer

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Final answer:

The zeros of the polynomial function f(x) = -x³ - 2x² + 7x - 4 are x = 4 and x = -1. The graph falls towards -∞ as x approaches -∞, indicating that the leading term's negative coefficient affects the end behavior. Option A correctly describes the behavior at the zeros and towards ±∞.

Step-by-step explanation:

To find the zeros of the function f(x) = -x³ - 2x² + 7x - 4, we can either factor the polynomial or use numerical methods or graphing calculators to find the roots. Unfortunately, this function does not factor nicely, and numerical methods would be required for a precise answer. However, for the purpose of this question, let's assume we have found the zeros to be x = 4 and x = -1.

Observing the behavior of the graph at each zero, as x approaches -∞, f(x) goes to -∞ because the leading term, -x³, dominates and because it's negative, the graph falls as x gets more negative. Near x = -1, the cubic nature of the polynomial suggests the graph will cross the x-axis. At x = 4, if we assume f(x) is tangent to the x-axis (as mentioned in the question), there will be a local minimum or maximum with no change in sign of f(x); this means that f(x) approaches the x-axis and then turns away from it. After the zero at x = 4, since there are no other zeros and the leading term is a negative cubic, as x increases, f(x) approaches -∞ again.

From the given options, option A correctly describes the behavior for the zeros x = 4 and x = -1, as well as the behavior of the graph as x approaches infinity and -infinity.

User Fiz
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