Factor compeletly and find all the zeros for these twp polyn
Factor compeletly and find all the zeros for these twp polynomial.
1- F(x) = 3x4-5x3-9x2+40x-12
2- G(x) = 3x3-5x2-8x-2
with the steps please.
Solution
1) f(x) = 3x^4 - 5x^3 - 9x^2 + 40x - 12
setting the equation equal to 0 to find the zeros
3x^4 - 5x^3 - 9x^2 + 40x - 12 = 0
solving teh equation for x
the function cannot be factored and it has no rational roots by rational root thorem
so applying quartic formula to find zeros of the function
we get two real zeros of the function
x1 = .3277
x2 = -2.3456
and two complex zeros
x3 = 1.84+1.345 i
x4 = 1.84 - 1.345 i
2) g(x) = 3x^3 - 5x^2 - 8x - 2
3x^3 - 5x^2 - 8x - 2 = 0
according to rational root test
possible rational roots are + - { 1 , 2 } / ( 1 , 3 }
+ - 1 , +- 1/3 , +- 2 , +- 2/3
at x = -1/3 g(x) becomes 0
hence one actual zero is x = -1/3
dividing g(x) by 3x +1
we get x^2 - 2x - 2
applying quadratic formula to find other two zeros
x = { -b +- b^2 - 4ac } / 2a
x = { 2 + - sqrt ( 4 + 4 } / 2 }
x 2 = 1 + sqrt 3
x3 = 1- sqrt 3
therefore,
3 zeros are
x1 = -1/3
x2 =1+ sqrt 3
x3 = 1 - sqrt 3

