a)
\sqrt2 x-2=\sqrt2-1
\sqrt2x=\sqrt2-1+2
\sqrt2x=\sqrt2+1
x=\frac{\sqrt2+1}{\sqrt2}
x=\frac{(\sqrt2+1)*\sqrt2}{\sqrt2*\sqrt2}
x=\frac{2+\sqrt2}{2}
b)
\sqrt{15}x-\sqrt5=\sqrt5x+\sqrt{20}
\sqrt3*\sqrt5x-\sqrt5=\sqrt5x+\sqrt4*\sqrt5/:\sqrt5
\sqrt3x-1=x+\sqrt4
\sqrt3x-x=2+1
x(\sqrt3-1)=3
x=\frac{3}{\sqrt3-1}=\frac{3(\sqrt3+1)}{(\sqrt3-1)(\sqrt3+1)}
x=\frac{3(\sqrt3+1)}{3-1}
x=\frac{3(\sqrt3+1)}{2}
c)
\sqrt6z-\sqrt3=\sqrt{12}-\sqrt3z
\sqrt2*\sqrt3z-\sqrt3=\sqrt4*\sqrt3-\sqrt3z/:\sqrt3
\sqrt2z-1=\sqrt4-z
\sqrt2z+z=2+1
z(\sqrt2+1)=3
z=\frac{3}{\sqrt2+1}
z=\frac{3(\sqrt2-1)}{(\sqrt2+1)(\sqrt2-1)}
z=\frac{3(\sqrt2-1)}{2-1}
z=3(\sqrt2-1)