Answer:
The zeros of the polynomial function f(x) = x^4 - 2x^3 - 8x^2 + 10x + 15 are x = -1, x = 3 + √29/2, x = 3 - √29/2, and x = -0.4495 (approximately).
Explanation:
To find all the zeros of the polynomial function f(x) = x^4 - 2x^3 - 8x^2 + 10x + 15, we can use the Rational Root Theorem and synthetic division.
Write the polynomial function in descending order of degree: f(x) = x^4 - 2x^3 - 8x^2 + 10x + 15.
Use the Rational Root Theorem to generate a list of possible rational zeros: ±1, ±3, ±5, ±15.
Use synthetic division to test each possible zero. We start with x = 1:
1 │ 1 -2 -8 10 15
│ 1 -1 -9 1
└───────────────
1 -1 -9 1 16
x = 1 is not a zero of the polynomial function.
We continue testing the remaining possible zeros:
-1 │ 1 -2 -8 10 15
│ -1 3 5 -15
└───────────────
1 -3 -3 15 0
Since the remainder is zero, we have found a zero of the polynomial function at x = -1.
We can use synthetic division to factor the polynomial function:
(x + 1)(x^3 - 3x^2 - 6x + 15)
Now we can solve for the remaining zeros of the polynomial function by factoring the cubic equation using the Rational Root Theorem and synthetic division:
3 │ 1 -3 -6 15
│ 3 0 -18
└─────────────
1 0 -6 -3
x = 3 is not a zero of the polynomial function.
-3 │ 1 -3 -6 15
│ -3 18 -36
└────────────
1 -6 12 -21
x = -3 is not a zero of the polynomial function.
The only remaining possible rational zeros are ±1/2 and ±5/2, but testing these values using synthetic division does not yield any more zeros.
However, we can see that the polynomial function can be factored as follows:
(x + 1)(x - 3)(x^2 - 3x - 5)
We can solve for the remaining zeros of the polynomial function by factoring the quadratic equation using the quadratic formula or factoring by grouping. Either way, we find that the remaining zeros are approximately x = (3 + √(29))/2 and x = (3 - √(29))/2.
Therefore, the zeros of the polynomial function f(x) = x^4 - 2x^3 - 8x^2 + 10x + 15 are x = -1, x = 3 + √29/2, x = 3 - √29/2, and x = -0.4495 (approximately).
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