Question 1113622
.
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{{{graph( 330, 330, -5.5, 5.5, -30.5, 5.5,
          x^4+4x^3-x^2-16x-12
)}}}


Plot y = {{{x^4+4x^3-x^2-16x-12}}}


The roots are -3, -2, -1 and 2.


You can check it manually.


The rational root theorem says that the rational / integer roots are anomg the divisors of the constant term "-12",

and voila: they all are there !  The plot visualizes them momentarily !
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