This polynomial can be factored by factoring pairs of terms.
= (4x³ -12x²) +(7x -21)
= 4x²(x -3) +7(x -3)
= (4x² +7)(x -3)
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<em>Additional comment</em>
The answer choices suggest we're not interested in irrational or complex factors. The quadratic (4x² +7) could be factored into linear terms involving irrational complex numbers. The form for "difference of squares" would be used for the purpose.
