Question

Determine the zeros of f(x) = x3 – 12x2 + 28x – 9
help please:)

Answer 1

1 -12 28 -9
0 <-- add these
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x ) 1 <- multiply these

your "x" will be whatever you wanna test for a zero

Answer 2

1,3,9 loos to be our options

Answer 3

1 -12 28 -9
0 3 -27 3
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3 ) 1 -9 1 -6: -6 is NOT a zero so "3" is out

Answer 4

1 -12 28 -9
0 -3 45
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-3 ) 1 -15 ...... this aint gonna zero out either

Answer 5

1 -12 28 -9
0 9 -27 9
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9 ) 1 -3 1 0 : x=9 works as a zero

Answer 6

x^2 -3x +1 is a quadratic form now that can be done with the quad formula if need be

Answer 7

thank you!

Answer 8

If guess that one of the roots is rational, the possible roots from the rational root theorem are ±1 , ±3 , ±9.

If I try x = 9, I find that f(9) = 0.

x^3 - 12x^2 + 28x - 9 = (x-9)(x^2 - 3x + 1)

Using the quadratic formula, the other 2 solutions are (3 ± sqrt(9-4))/2 = (3 ± sqrt(5))/2

Solutions to f(x) = 0 : 9 , (3 + sqrt(5))/2 , (3 - sqrt(5))/2

Answer 9

youre welcome :)

Answer 10

understand?

Answer 11

yes thank you:)