Consider the equation 4 x to the 4th power minus 8 x cubed plus 4 x squared minus 128 x minus 960 is equal to 0 The real solutions are 5 and negative 3 What are the nonreal solutions?

The two real roots give the factor (x − 5)(x + 3) = x² − 2x − 15. Dividing the equation’s polynomial by this factor leaves 4(x² + 16) = 0. Thus x² = −16, so the nonreal solutions are −4i and 4i, matching choice D.

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