用配方法证明5x²-6x+11的值为非负数

问题描述:

用配方法证明5x²-6x+11的值为非负数

5x²-6x+11
=5(x²-6x/5)+11
=5(x-3/5)²+11-9/5
=5(x-3/5)²+46/5;
∵(x-3/5)²≥0;
∴5x²-6x+11≥46/5;
所以是非负数
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