How do you find all the zeros of #F(x)=x^3-3x^2+9x+13#?
1 Answer
Mar 5, 2016
Identify
Explanation:
First notice that reversing the signs of the coefficients of the terms with odd degree results in coefficients that sum to zero.
That is
So
#x^3-3x^2+9x+13#
#= (x+1)(x^2-4x+13)#
#=(x+1)(x^2-4x+4+9)#
#=(x+1)((x-2)^2-(3i)^2)#
#=(x+1)((x-2)-3i)((x-2)+3i)#
#=(x+1)(x-2-3i)(x-2+3i)#
So the zeros of