已知| a | =" |" b | =" 2," a·b =" -2," 且(a + b)⊥(a + b), 则实数的值为A．–1B．1C．–2D．2

题型：不详难度：来源：

已知| a | =" |" b | =" 2," a·b =" -2," 且(a + b)⊥(a + b), 则实数的值为

A．–1

B．1

C．–2

D．2

答案

A

解析

本题考查向量垂直,向量的数量积.
因为所以即
；所以，解得故选A