a)
\sqrt2-1=(\sqrt3-3x)(\sqrt2+4)
\sqrt2-1=\sqrt6+4\sqrt3-3\sqrt2x-12x
12x+3\sqrt2=1-\sqrt2+4\sqrt3+\sqrt6
x(12+3\sqrt2)=1-\sqrt2+4\sqrt3+\sqrt6
x=\frac{1-\sqrt2+4\sqrt3+\sqrt6}{12+3\sqrt2}
x=\frac{1-\sqrt2+4\sqrt3+\sqrt6}{3(4+\sqrt2)}
b)
x-3=x\sqrt2-3\sqrt3
x-x\sqrt2=3+3\sqrt3
x(1-\sqrt2)=3+3\sqrt2
x=\frac{3+3\sqrt2}{1-\sqrt2}=\frac{(3+3\sqrt2)(1+\sqrt2)}{(1-\sqrt2)(1+\sqrt2)}
x=\frac{3+3\sqrt2+3\sqrt2+3\sqrt6}{1-2}
x=\frac{3+6\sqrt2+3\sqrt6}{-1}
x=-3(1+2\sqrt2+\sqrt6)