4.S=t⁵ - t³V(t)=S ' =5t⁴ - 3t²V(2)=5*2⁴ - 3*2² = 5*16 - 3*4 = 80-12= 68 (м/с)5.f(x)=12x-x³f ' (x)=12 -3x²12-3x²≤03x²-12≥03(x²-4)≥0x²-4≥0(x-2)(x+2)≥0x=2 x= -2 + - +------ -2 ----------- 2 ------------\\\\\\\\ \\\\\\\\\\\\\x∈(-∞; -2]U[2; +∞)6.f(x)=cos2x+x√3f ' (x)= -2sin2x +√3-2sin2x+√3=0-2sin2x= -√3sin2x= √3/22x= (-1)ⁿ (π/3) + πnx=(-1)ⁿ (π/6) + (π/2)n, n∈ZПри n=0 x=π/6При n=1 x= -π/6 + π/2 = 2π/6 = π/3При n=2 x= π/6 + π = 7π/6При n=3 x= -π/6 + 3π/2 = 8π/6=4π/3При n=4 x=π/6 + 2π= 13π/6При n=5 x=-π/6 + 5π/2 = 14π/6=7π/3При n=6 x=π/6 + 3π= 19π/6При n=7 x=-π/6 +7π/2=20π/6=10π/3Ответ: π/6; π/3; 7π/6; 4π/3; 13π/6; 7π/3; 19π/6; 10π/3.