SOLUTION: Find the value of a for which the polynomial x^3 − ax + 8 has the root x = −2. and find the other roots of the polynomial. (hint: the others are not rational)

Question 1013900: Find the value of a for which the polynomial x^3 − ax + 8 has the root x = −2. and find the other roots of the polynomial. (hint: the others are not rational)
Answer by fractalier(6550) (Show Source): You can put this solution on YOUR website!
I'm thinking that if -2 is a root, then
(-2)^3 - ax + 8 = 0
a = 0
Therefore we can divide x^3 + 8 by x + 2 and get

And you can use the quadratic formula to solve
x^2 - 2x + 4 = 0

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SOLUTION: Find the value of a for which the polynomial x^3 &#8722; ax + 8 has the root x = &#8722;2. and find the other roots of the polynomial. (hint: the others are not rational)

SOLUTION: Find the value of a for which the polynomial x^3 − ax + 8 has the root x = −2. and find the other roots of the polynomial. (hint: the others are not rational)