(f-g)(x) will be 3x^2 -2x+4 -(5x^2+6×-8) distribute the -sign, gives us 3x^2-2x+4-5x^2-6x+8, now combine like terms and should get, -2x^2-8x+12, final answer, (f-g)(x)= -2x^2-8x+1×, hope it helped, good luck
F(x) - g(x). We will subtract the terms and negate everything on the g(x) side as it is subtraction. We get 3x^2 - 2x +4 -5x^2 -6x +8 which equals -2x^2 +6x +12