a)
[tex]a=-0,5, \ b=0,2\\\\a^2+b^2=(-0,5)^2+(0,2)^2=(-0,5)\cdot(-0,5)+0,2\cdot0,2=0,25+0,04=0,29[/tex]
b)
[tex]x=-1, \ y=\frac{1}{6}, \ z=-6\\\\\sqrt{-4x^3+12y-5z}=\sqrt{-4\cdot(-1)^3+12\cdot\frac{1}{6}-5\cdot(-6)}=\\\\=\sqrt{-4\cdot(-1)+\frac{12}{6}+30}=\sqrt{4+2+30}=\sqrt{36}=\sqrt{6^2}=6[/tex]