Help on my pre-cal homework?

Determine the x values that cause the polynomial function to be (a) zero, (b) positive, and (c) negative.

1. f(x) = (2x^2 + 5)(x - 8)^2(x + 1)^3

2. f(x) = (x + 2)^3(4x^2 + 1)(x - 9)^4

1 Answer

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  • 8 years ago
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    1. 2x^2 + 5 will never = 0; x - 8 = 0 if x = 8, and x + 1 = 0 if x = -1

    Only (x + 1)^3 could ever be negative so as long as x > -1, it's positive, but if x < -1 it's negative.

    2. x + 2 = 0 if x = -2; 4x^2 + 1 can never be 0, and x - 9 = 0 if x = 9

    Only (x + 2)^3 can be negative, so if x > -2 it's positive, but if x < -2 it's negative.

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