перемножить (2x+7)*(x+6)*(x-3)

= (2x^2 + 12x + 7x + 42)(x - 3) = 
= (2x^2 + 19x + 42)(x - 3) = 
= 2x^2(x - 3) + 19x(x - 3) + 42(x - 3) = 
= 2x^3 - 6x^2 + 19x^2 - 57x + 42x - 126 = 
= 2x^3 + 13x^2 - 15x - 126