-1 i -1/6
Пошаговое объяснение:
f'(x) = 12х²+14х+2
2*(6x²+7x+1)=0
6x²+7x+1=0
D = 7²-4*6*1 = 49-24 = 25
√D = 5
X1=(-7-5)/2*6 = -12/12 = -1
X2 = (-7+5)/12 = -2/12 = -1/6
