What is the completely factored form of f of x is equal to 6 x cubed minus 13 x squared minus 4 x plus 15 ?

Substitute x = -1 into the polynomial: 6(-1)³ − 13(-1)² − 4(-1) + 15 = 0, so (x + 1) is a factor. Dividing gives 6x² − 19x + 15, which factors as (2x − 3)(3x − 5). Therefore, the completely factored form is (x + 1)(2x − 3)(3x − 5), choice D.

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