Odpowiedź :
Hej!
a]
[tex](a+b)+(2a-b)-(a-2b)=\\\\=a+b+2a-b-a+2b=\\\\=\boxed{2a+2b}[/tex]
b]
[tex](3x-y+1)-(x+y)+(y-x)=\\\\=3x-y+1-x-y+y-x=\\\\=\boxed{x-y+1}[/tex]
c]
[tex]-(2a^2-3ab)-(2b-3a^2)+(-ab-b)=\\\\=-2a^2+3ab-2b+3a^2-ab-b=\\\\=\boxed{a^2+2ab-3b}[/tex]
d]
[tex]-(kx+my)-(3kx+2my)-(5kx-3my)=\\\\=-kx-my-3kx-2my-5kx+3my=\\\\=\boxed{-9kx}[/tex]
e]
[tex](2x-3y)+(2y-3x)-(x-y)=\\\\=2x-3y+2y-3x-x+y=\\\\=\boxed{-2x}[/tex]
f]
[tex](4x-2xy-1)-(-5x+xy+1)=\\\\=4x-2xy-1+5x-xy-1=\\\\=\boxed{-3xy+9x-2}[/tex]
g]
[tex](x+y)+(x-y)=\\\\=x+y+x-y=\\\\=\boxed{2x}[/tex]
Pozdrawiam! - Jula
3.
[tex]a)\\(a+b)+(2a-b) - (a-2b) = a+b+2a-b-a+2b = 2a+2b\\\\b)\\(3x-y+1)-(x+y)+(y-x) = 3x-y+1-x-y+y-x = x-y+1\\\\c)\\-(2a^{2}-3ab)-(2b-3a^{2})+(ab-b) = -2a^{2}+3ab-2b+3a^{2}-ab-b = a^{2}+2ab-3b\\\\d)\\-(kx+my)-(3kx+2my)-(5kx-3my) = -kx-my-3kx-2my-5kx+3my=\\\\=-9kx[/tex]
[tex]e)\\(2x-3y)+(2y-3x)-(x-y) = 2x-3y+2y-3x-x+y=-2x\\\\f)\\(4x-2xy-1)-(-5x+xy+1) = 4x-2xy-1+5x-xy-1 = 9x-3xy-2\\\\g)\\(x+y)+(x-y) = x+y+x-y = 2x[/tex]