2 1 a 5 b 6 2 2a+4 4a+18 8a+2b+36 ------------------------------------- 1 a+2 2a+9 4a+b+18 8a+2b+42 -1 1 a 5 b 6 -1 -a+1 a -6 -a-b+ 6 ------------------------------------- a-1 -a+6 a+b-6 -a-b+12 8a + 2b + 42 = 16 -a - b + 12 = 10 8a + 2b = -26 -a - b = - 2 8a + 2b = -26 -2a - 2b = - 4 6a = -30 a = - 5