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2013年是湖北省实行新课标考试的第二年,命题方式基本稳定,如填空题中的第13题与2012年湖北卷第6题,本质相同,且是由课本选修4-5第三讲第二部分例3原题改编.试题设x、y、z∈R,且满足:x2+y2+z2=1、x+2y+3z=14(1/2),则x+y+z=.本题意在考察柯西不等式的性质,以考察考生的运算求解能力和逻辑推理能力.解析根据柯西不等式可得(x2+y2+z2)(12+22+32)≥(x+2y+3z)2
2013 is the second year of the implementation of the new curriculum standard examination in Hubei Province, the propositional approach is basically stable. For example, the 13th title in the blank school title is the same as the 6th volume in the Hubei volume in 2012, The second part of the example of the original 3 adapted. Test questions set x, y, z∈R, and satisfy: x2 + y2 + z2 = 1, x +2 y +3 z = 14 (1/2), then x + y + z =. The purpose of this paper is to examine the nature of Cauchy’s inequality in order to examine the candidate’s ability of solving and logical reasoning.According to Cauchy’s inequality, we can get (x2 + y2 + z2) (12 + 22 + 32) ≥ (x + 2y + 3z) 2