Даю 98 баллов, срочно надо

Решите задачу:

$4)\; \; \left \{ {{y=2-x^2} \atop {x-y=0}} \right.\; \left \{ {{y=2-x^2} \atop {y=x}} \right. \; \left \{ {{2-x^2=x} \atop {y=x}} \right.\; \left \{ {{x^2+x-2=0} \atop {y=x}} \right.\; \left \{ {{x_1=-2\; ,\; x_2=1} \atop {y_1=-2\; ,\; y_2=1}} \right. \\\\Otvet:\; \#3:\; \; (-2,-2)\; ,\; (1,1)\; .\\\\\\5)\; \; \left \{ {{x+y=5} \atop {x^2-y^2=20}} \right.\; \left \{ {{x+y=5} \atop {(x-y)(x+y)=20}} \right.\; \left \{ {{x+y=5} \atop {(x-y)\cdot 5=20}} \right.\; \; \Rightarrow \; \; x-y=4$

$6)\; \; \left \{ {{x\, (x-3)=0} \atop {x-2y=4}} \right.\; \left \{ {{x_1=0\; ,\; x_2=3} \atop {2y=x-4}} \right. \; \left \{ {{x_1=0\; ,\; x_2=3} \atop {y_1=-2\; ,\; y_2=-0,5}} \right.\\\\Otvet:\; \#3:\; \; (0,-2)\; ,\; (3,-0,5)\; .$