`a)M` có nghĩa khi `x≥0` `b)M=((\sqrt{x}-2)/2+(1-2\sqrt{x})/4).(4(x-1))/3` `=>M=((6(\sqrt{x}-2))/12+(3(1-2\sqrt{x}))/12).(4(x-1))/3` `=>M=((6\sqrt{x}-12)/12+(3-6\sqrt{x})/12).(4(x-1))/3` `=>M=(6\sqrt{x}-12+3-6\sqrt{x})/12.(4(x-1))/3` `=>M=(-3)/4.(4(x-1))/3` `=>M=-(x-1)` `=>M=1-x` Vậy : `M=1-x`
