Find all real and complex roots for the following polynomlal
Find all real and complex roots for the following polynomlals. IlI. Theorem to identify potential roots. the Ration Ul 17, g(x)=xt-1
Solution
A.
x^3 - 1 = 0
we can see that x = 1 is the first root of equation
x1 = 1
the (x^3 - 1)/(x - 1) = x^2 + x + 1
Now the roots of
x^2 + x + 1 = 0
will be
x = [-1 +/- sqrt (1^2 - 4*1*1)]/2
x2 = [-1 + sqrt 3]/2
x3 = [-1 - sqrt 3]/2
17.
x^4 - 1 = 0
(x^2)^2 - 1^2 = 0
Now we know that
a^2 - b^2 = 0,
then
(a - b)(a + b) = 0
So,
(x^2 - 1)(x^2 + 1) = 0
x^2 - 1 = 0
x = +1 or x = -1
x^2 + 1 = 0
x^2 = -1
x = (-1)^0.5
then x = +i Or x = -i
