SOLUTION: The number x=-2i is a zero of polynomial P(x)=x^4+2x^3+x^2+8x-12. Find all four zeros of this polynomial. I have -3, -2, and 1

Question 762649: The number x=-2i is a zero of polynomial P(x)=x^4+2x^3+x^2+8x-12. Find all four zeros of this polynomial.
I have -3, -2, and 1
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
Your found root of -2 is wrong.

You should find through Rational Roots Theorem and synthetic division, roots of -3, +1, and then you still would have a quadratic binomial of . Solving the equation for x will give you and

Briefly, you should have made a process roughly equivalent to this:
Check for root -3;
Remainder 0, quotient
Check for root +1;
Remainder 0, quotient
Solve the quadratic for its roots and find they are and .
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