Question

设A={xIx平方-4x-5=0},B=(xIx平方=1},求AUB,AnB

Answer 1

x² - 4x - 5 = 0

(x + 1)(x - 5) = 0

x = -1 或 x = 5

所以 A = { -1 ,5 }

x² = 1

x = 1 或 x = -1

所以 B = { 1 ,-1 }

所以 AUB = { -1 ,1 ,5}

A∩B = { - 1 }