f(x)=m/3x^3+x^2-xf'(x)=mx^2+2x-1m>0 -1/m+√(4+4m)/(2m)<2-2+√(4+4m)<4m√(4+4m)<4m+24+4m<16m^2+16m+44m^2+3m>0∴m>0
