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3x^4-19x^3+39x^2-29x+6 what is the 3 rational roots

0 votes

i need the answer.

asked Feb 24, 2014 in ALGEBRA 2 by angel12 Scholar

3 Answers

0 votes

Given polynomial is 3x^4-19x^3+39x^2-29x+6

By synthatic division,

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answered Feb 25, 2014 by dozey Mentor
0 votes

Identify Rational Zeros 

3x 4 -19x + 39x– 29x + 6 = 0

Rational Root Theorem, if a rational number in simplest form p/q is a root of the polynomial equation anxn + an  1xn – 1 + ... + a1x + a0 = 0, then p is a factor of a0 and q is a factor if an.

If p/q is a rational zero, then p  is a factor of 6 and is a factor of 3.

The possible values of are   ± 1,  ± 2, ± 3,± 6 .

The possible values for q  are ± 1, ± 3.

By the Rational Roots Theorem, the only possible rational roots are, p/q = ± 1, ± 2, ± 3, ± 1/3, ± 2/3.

Make a table for the synthetic division and test possible real zeros.

p/q

3

-19

39

-29

6

-1

3

-22

61

90

-84

1

3

-16

23

-6

0

Since f (1) = 0, x = 1 is a zero. The depressed polynomial is  3x 3 -16x 2 + 23x - 6 = 0.

answered May 15, 2014 by david Expert
0 votes

Contonuous...

Now 3x 3 -16x 2 + 23x - 6 = 0.

If p/q is a rational zero, then p is a factor of 6 and q is a factor of 3.

By the Rational Roots Theorem, the only possible rational roots are, p/q = ± 1, ± 2, ± 3, ± 1/3, ± 2/3 .

Make a table for the synthetic division and test possible real zeros.

p/q

3

-16

23

-6

1

3

-13

10

4

-1

3

-19

42

-48

-2

3

-22

67

-140

2

3

-10

3

0

Since f (2)  =  0,  x = 2 is a zero. The depressed polynomial is  3x– 10x + 3 = 0.

Now factorise 3x– 10x + 3 = 0.

3x – 9x - x + 3 = 0

3x (x - 3) - 1(x - 3) = 0

(x - 3) (3x - 1) = 0

Apply zero product property.

x - 3 = 0 and 3x - 1 = 0

x = 3 and 3x = 1

x = 3 and x = 1/3

Rational roots of the 3x 4 -19x + 39x– 29x + 6 = 0 are x = 1 , 2 , 3 and 1/3.

answered May 15, 2014 by david Expert

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