Respuesta :

completely factored it is (12x^2 + 4)(x-5)
= 4(3x^3 - 15x^2 + x - 5)

 product of first coefficient and -5 is -15  so  one factor could be x +/ 3) or x +/- 5)

using the factor theorem   f(5) =  375 - 375=5-5 = 0  so (x - 5) is a factor:-

so we have  4(x - 5)(3x^2 + 1)   Answer