Ответ:

3)

-x2 + 4x = - 3.

y - 2y = - 5.

-x(x-4) = - 3

-y = - 5 y=5

-x = - 3

x=3

x-4 = - 3

x= 1

1)

0,5x+x2=2

-y-2y= -1

X(0,5+x) = 2

-3y= - 1

X=2

0,5+x=2 x=1,5

3y=1 y= - 2