4.
[tex]dla \ \ 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+2+30} =\\\\= \sqrt{36} = 6[/tex]
5.
[tex]\frac{1}{3}ab^{2} = -\frac{1}{3} \ \ /\cdot\frac{3}{1}\\\\ab^{2} = -1\\\\Np: \ a = -1 \ i \ b = -1\\\\-1\cdot(-1)^{2} = -1[/tex]
