(1)y=x(1-x)3x-3>01/(x-3)+(x-3)+3>=2[(1/(x-3)*(x-3)]+3=5(4)bc/a+ac/b+ab/c=(bc)^2/abc+(ac)^2/abc+(ab)^2/abc=[(ab)^2+(bc)^2+ac)^2]/abc=[2(ab)^2+2(bc)^2+2(ac)^2]/2abc(ab)^2+(bc)^2>=2(ab*bc)(ac)^2+(bc)^...