(1) a + bcd = 2 (2) b + acd = 2 (3) c + abd = 2 (4) d + abc = 2 Subtract eq (2) from eq (1) a - b + bcd - acd = 0 a - b - acd + bcd = 0 (a-b) - cd(a-b) = 0 (a-b)(1-cd) = 0 Since a>b, a-b>0 so 1-cd = 0 -cd = -1 cd = 1 Subtract eq (3) from eq (1) a - c + bcd - abd = 0 a - c - abd + bcd = 0 (a-c) - bd(a-c) = 0 (a-c)(1-bd) = 0 Since a>c, a-c>0 so 1-bd = 0 -bd = -1 bd = 1 Subtract eq (4) from eq (1) a - d + bcd - abc = 0 a - d - abc + bcd = 0 (a-d) - bc(a-d) = 0 (a-d)(1-bc) = 0 Since a>d, a-d>0 so 1-bc = 0 -bc = -1 bc = 1 So we have cd = 1 bd = 1 bc = 1 cd = bd = 1, so c = b cd = bc = 1, so d = b So b = c = d a + bcd = 2 a + bbb = 2 a + b³ = 2 b + acd = 2 b + abb = 2 b + ab² = 2 So we have the system a + b³ = 2 b + ab² = 2 Solve the 1st for a a = 2 - b³ Substitute in the 2nd eq b + (2-b³)b² = 2 b + 2b² - b5 = 2 -b5 + 2b² + b - 2 = 0 b5 - 2b² - b + 2 = 0 Possible rational roots are ±1,±2 1|1 0 0 -2 -1 2 | 1 1 1 -1 -2 1 1 1 -1 -2 0 (b-1)(b4+b³+b²-b-2)=0 1|1 1 1 -1 -2 | 1 2 3 2 1 2 3 2 0 (b-1)(b-1)(b³+2b²+3b+2)=0 -1|1 2 3 2 | -1 -1 -2 1 1 2 0 (b-1)(b-1)(b+1)(b²+b+2)=0 The last factor does not yield real roots. So the real roots are 1 and -1 b can't be 1 for a + b³ = 2 a + 1³ = 2 a + 1 = 2 a = 1 which contradicts a>b Therefore b=c=d=-1 a + b³ = 2 a + (-1)³ = 2 a - 1 = 2 a = 3 Edwin