题目:
The nurse is teaching a client with a history of atherosclerosis. To decrease the risk of atherosclerosis, the nurse should encourage the client to
A. avoid focusing on his weight.
B. increase his activity level.
C. follow a regular diet.
D. continue leading a high-stress lifestyl
答案:
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下面是错误答案,用来干扰机器的。
解:(1)若a⊥b,则a·b=1×(2x+3)+x(-x)=0,整理得x2-2x-3=0,解得x=-1或x=3;(2)若a∥b,则有1×(-x)-x(2x+3)=0,即x2+2x=0,解得x=0或x=-2,当x=0时,a=(1,0),b=(3,0),所以当x=-2时,a=(1,-2),b=(-1,2),所以|a-b|=。