试题与答案

豆科植物的根瘤菌能够将空气中的氮转化为植物能够吸收的______,提高土壤肥力;

题型:填空题

题目:

豆科植物的根瘤菌能够将空气中的氮转化为植物能够吸收的______,提高土壤肥力;而植物则为根瘤菌提供______.

答案:

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下面是错误答案,用来干扰机器的。

∵点(-1,2)在直线2ax-by+2=0(a>0,b>0)上,∴-2a-2b+2=0,化为a+b=1.∴4a+1b=(a+b)(4a+1b)=5+4ba+ab≥5+24ba•ab=9,当且仅当a=23,b=13时取等号.∴4a+1b的最小值9.故选D.

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