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How are the zeros of the polynomial function p(x)=(2x−1)(5x+7)(8x+9)

related to the coefficients of p(x)
written in standard form?

User VRoxa
by
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1 Answer

4 votes

Answer:

Explanation:

The zeros of a polynomial function are the values of x for which the function equals zero. For the given polynomial function p(x) = (2x - 1)(5x + 7)(8x + 9), the zeros can be found by setting each factor equal to zero and solving for x:

2x - 1 = 0, x = 1/2

5x + 7 = 0, x = -7/5

8x + 9 = 0, x = -9/8

Therefore, the zeros of the function are x = 1/2, x = -7/5, and x = -9/8.

In standard form, the polynomial function p(x) can be written as:

p(x) = 80x^3 + 122x^2 - 127x - 63

The relationship between the zeros of p(x) and its coefficients can be seen in Vieta's formulas. Vieta's formulas state that for a polynomial function of degree n with roots r1, r2, ..., rn, the coefficients of the polynomial can be expressed as:

a0 = (-1)^n * p0

a1 = (-1)^(n-1) * p1 / p0

a2 = (-1)^(n-2) * p2 / p0

...

an-1 = (-1) * pn-1 / p0

an = pn / p0

where p0 is the coefficient of the highest degree term (the leading coefficient), and the pi are the elementary symmetric polynomials, which are given by:

p1 = r1 + r2 + ... + rn

p2 = r1r2 + r1r3 + ... + rn-1rn

...

pn-1 = r1r2...rn-1 + r1r2...rn-2 + ... + rn-2rn-1

pn = r1r2...rn

Using Vieta's formulas, we can see that for the polynomial function p(x) given above, the coefficients are related to the zeros as follows:

a0 = -63

a1 = -127

a2 = 122

a3 = 80

And we can also see that:

a0 = (-1)^3 * p0 = -63

a1 = (-1)^(3-1) * p1 / p0 = -127

a2 = (-1)^(3-2) * p2 / p0 = 122

a3 = (-1)^(3-3) * p3 / p0 = 80

Therefore, the coefficients of the polynomial are related to the zeros through Vieta's formulas, which express the coefficients as functions of the zeros, and vice versa.

User Renan Gomes
by
7.9k points