a)$f(x)=x^{2}-2x-3x^{2}-x=-2x^{2}-3x=0\Rightarrow x\in$ {$0;\frac{-3}{2}$}b)$g(x)=(3-x^{2})(x-1)=0\Rightarrow x\in ${$\sqrt{3};-\sqrt{3};1$}
c)$h(x)=x(3-2x)+x(3-2x)=2x(3-2x)=0\Rightarrow x\in ${$0;\frac{3}{2}$}
d)$k(x)=(x-1)(x+5)=0\Rightarrow x\in ${$1;-5$}