(x+2) is a factor of

From the factor theorem, we have


(x + 2) is the factor of f(x) if (f-2) = 0


Here, we have


f(-2) = (-2)4 – (-2)2 – 12


= 16 – 4 – 12


= 16 – 16


= 0


Therefore,


(x + 2) is a factor of (x4 – x2 – 12)


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