1)х-2y-а(2y-х)=(x-2y)+a(x-2y)=(x-2y)(1+a)
2)4(3a+2b)^2-(3а-2b)^2=(6a+4b)²-(3a-2b)²=
(6a+4b+3a-2b)(6a+4b-3a+2b)=
(9a+2b)(3a+6b)=3(9a+2b)(a+2b)
4(4-у^2)(y^2+4)-(5-y^3)^2+(4^4+y*4^2+16)(y^2-4)=
4(16-y^4)-25+10y^3-y^6+256y^2+16y^3+16y^2-1024-64y-64=
-y^6-4y^4+26y^3+272y^2-64y-1049
2x-8=0
2x=8
x=8/2
x=4