Question 1052462
From the graph, 
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*[illustration dfc15.JPG].
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the only real root is at {{{x=-0.75}}} so one of the factors is,
({{{4x+3}}}).
If you perform polynomial long division,
{{{(4x^3+3x^2+16x+12)/(4x+3)=x^2+4}}}
So then the remaining complex roots are {{{x=2i}}} and {{{x=-2i}}}.