решите неравентсво f'(x)больше 0
f(x)=-3xкубе+2xквадрат

f(x)=-3x³+2x²       f `(x)>0
f `(x)=-3*3x²+2*2x=-9x²+4x
-9x²+4x>0
9x²-4x <0
9x(x-4/9)<0
                 +                       -                                  +
_____________0________________4/9______________

x∈(0;4/9)