Odpowiedź :
a) a-a[a-(1-a]) = a-a(a-1+a) = a-a(2a-1) = a-2a²-a = -2a²
b) -x-[-(1-x)-(x-1)] = -x-(-1+x-x+1) = -x+1-x+x-1 = -x
c) x-[y-(x-y)-x-(y-x)] = x-(y-x+y-x-y+x) = x-y+x-y+x+y-x = 2x-y
d) 1-a-[1-(a-1)-2a-(1-3a)]-a-1 = 1-a-(1-a+1-2a-1+3a)-a-1 = 1-a-1+a-1+2a+1-3a = -a
b) -x-[-(1-x)-(x-1)] = -x-(-1+x-x+1) = -x+1-x+x-1 = -x
c) x-[y-(x-y)-x-(y-x)] = x-(y-x+y-x-y+x) = x-y+x-y+x+y-x = 2x-y
d) 1-a-[1-(a-1)-2a-(1-3a)]-a-1 = 1-a-(1-a+1-2a-1+3a)-a-1 = 1-a-1+a-1+2a+1-3a = -a