U = {x | log ⅓ (x² - 3x + 5) > -2 ,x∈Z} = {x | x²-3x+5 < 9 ,x∈Z}
= {x | -1 < x < 4 ,x∈Z} = {0 ,1 ,2 ,3}
A = {x | x² - (a + 2)x + a + 1 = 0} = {1 ,a + 1}
B = {x | x² - 3x = 0} = {0 ,3}
CuA = B ,A = {1 ,2}
a +1 = 2
a = 1&#…符号是什么