[tex]a)\\
x+|x|=-3+|-3|=-3+3=0\\
x-2|x|=-3-2\cdot|-3|=-3-2\cdot3=-3-6=-9\\\\
b)\\
x=4-2\sqrt6\approx 4-2\cdot2,4=4-4,8=-0,8<0\\
x+|x|=4-2\sqrt6-(4-2\sqrt6)=4-2\sqrt6-4+2\sqrt6=0\\
x-2|x|=4-2\sqrt6+2\cdot(4-2\sqrt6)=4-2\sqrt6+8-4\sqrt6=12-6\sqrt2\\\\
c)\\
x=6\sqrt2-8\alpprox6\cdot 1,4-8=8,4-8=0,4>0\\
x+|x|=6\sqrt2-8+6\sqrt2-8=12\sqrt2-16\\
x-2|x|=6\sqrt2-8-2\cdot(6\sqrt2-8)=6\sqrt2-8-12\sqrt2+16=-6\sqrt2+8[/tex]
