The correct option is B 4, 5
f(x) = x2+14x+9xe+2x+3=1+12x+6x2+2x+3
f′(x)=(x2+2x+3)(12)−(12x−16)(2x+2)(x2+2x+3)2
= 12x2+24x+36−242−24x−12x−12(x2+2x+3)2
= 12x2−12x+24(x2+2x+3)2
= −12(x2+x−2)(x2+2x+3)2
f(x) is decreasing from (−∞,−2)U(1,∞) and increasing from (2, 1)