Y`=12x³+3x²=0
3x²(4x+1)=0
x=0∈[-3;2] U x=-1/4∈[-3;2]
<span>(2,7t+4,3)⋅(7t+8)=</span>18,9t²+21,6t+30,1t+34,4=18,9t²+51,7t+34,4
16*cos20°*cos40°*cos80°*sin20°=
=8*(2*sin20°*cos20°)*cos40°*cos80°=8*sin(2*20°)*cos40°*cos80°=
=4*(2*sin40°*cos40°)*cos80°=4sin80°*cos80°=2*(2sin80°*cos80°)=2*sin160°