设全集U={2,4,a²-2a-1},集合A={a+6,2},CuA={7},求实数a的值
问题描述:
设全集U={2,4,a²-2a-1},集合A={a+6,2},CuA={7},求实数a的值
答
a^2-2a-1 = 7
a + 6 = 4
so a = -2