题目

解方程：2x2﹣5x﹣1=0． 答案：【考点】解一元二次方程-公式法． 【分析】求出b2﹣4ac的值，再代入公式求出即可． 【解答】解：2x2﹣5x﹣1=0， b2﹣4ac=（﹣5）2﹣4×2×（﹣1）=33， x=， x1=，x2=． 【点评】本题考查了用公式法解一元二次方程的应用，能熟记公式是解此题的关键． The premier said the nation’s development should not only promote economic growth , but also pursue social fairness and justice to      every individual’s all-round development in a free environment.          A. urge     B. insure          C. ensure         D. satisfy