SOLUTION: What are the zeros of the polynomial function? {{{ f(x) = x^4 - 4x^3 - 22x^2 + 4x + 21 }}} Select EACH correct answer. A. -3 B. -1 C. 0 D. 1 E. 3 F. 7

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: What are the zeros of the polynomial function? {{{ f(x) = x^4 - 4x^3 - 22x^2 + 4x + 21 }}} Select EACH correct answer. A. -3 B. -1 C. 0 D. 1 E. 3 F. 7      Log On


   



Question 1127716: What are the zeros of the polynomial function?
+f%28x%29+=+x%5E4+-+4x%5E3+-+22x%5E2+%2B+4x+%2B+21+
Select EACH correct answer.
A. -3
B. -1
C. 0
D. 1
E. 3
F. 7

Found 2 solutions by greenestamps, josgarithmetic:
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


0 can't be a root; if it were, the constant term would be 0.

Test 1 and -1 by evaluating the polynomial at those values. It turns out f(1)=0 and f(-1)=0, so both are roots. Roots of 1 and -1 correspond to binomial factors of x-1 and x+1; factor them out by factoring, long division, synthetic division, or any other method you know.

x^4-4x^3-22x^2+4x+21 = (x-1)(x+1)(x^2-4x-21)

The remaining quadratic is easily factored:

x^4-4x^3-22x^2+4x+21 = (x-1)(x+1)(x-7)(x+3)

The roots are 1, -1, -3, and 7.

Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
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What are the zeros of the polynomial function?
+f%28x%29+=+x%5E4+-+4x%5E3+-+22x%5E2+%2B+4x+%2B+21+
Select EACH correct answer.
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Four of them easily found using synthetic division to check:
A, B, D, F.

A. -3
B. -1
C. 0
D. 1
E. 3
F. 7


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