问题描述: 不论x为何实数,多项式3x²-5x-1的值总大于2x²-4x-7的值 1个回答 分类:数学 2014-11-10 问题解答: 我来补答 (3x²-5x-1)-(2x²-4x-7)=3x²-5x-1-2x²+4x+7=x²-x+6=(x²-x+1/4)+6-(1/4)=(x-1/2)²+23/4∵(x-1/2)²≥0∴(3x²-5x-1)-(2x²-4x-7)=(x-1/2)²+23/4>0即:(3x²-5x-1)-(2x²-4x-7)>0∴(3x²-5x-1)>(2x²-4x-7)即:不论x为何实数,多项式3x²-5x-1的值总大于2x²-4x-7的值 展开全文阅读