Răspuns :
x = 2-3+5 = 4
y = -3+2-1 = -2
z= -5+2-9 = -12
t = 1-2-3-4 = -8
x-y+z-t = 4-(-2)+(-12)-(-8) = 4+2-12+8 = 2
y = -3+2-1 = -2
z= -5+2-9 = -12
t = 1-2-3-4 = -8
x-y+z-t = 4-(-2)+(-12)-(-8) = 4+2-12+8 = 2
x - y + z - t = 2 - 3 + 5
3 - 2 +1
-5 +2 - 9
-1 +2 +3 +4
-----------------------
= - 1 -1 +0 +4 = -2+4= +2
3 - 2 +1
-5 +2 - 9
-1 +2 +3 +4
-----------------------
= - 1 -1 +0 +4 = -2+4= +2