a)2x-3x+4x=(2-3+4)x=3x
b)-x-3x+2x-4x== -1x-3x+2x-4x=(-1-3+2-4)x=-6x
c)2*(x-y)+3(2x+y)=2x-2y+6x+3y=8x-2y+3y=8x+y
d)3(2x+y)-4(x-y)=6x+3y-4(x-y)=6x+3y-4x+4y=2x+3y+4y=2x+7y
e) x(x+y)-y(x-y)=x²+xy-xy+y²=x²+y²
f) x(4x-3y)-y(2x+y)=4x²-3xy-y(2x+y)=4x²-3xy-2xy-y²=4x²-5xy-y²
