1、GRE（ QUANTITATIVE）练习试卷 21及答案与解析 1 For-5-x 15, x=_ 2 For which values of x is 6x-3 4x+5? 3 If x=7, then is 3x+7 greater than or less than 5x-6? 4 For which values of x is 2x-5 -3x+20? 5 Solve for x: -4x+3 18 GRE（ QUANTITATIVE）练习试卷 21答案与解 析 1 【正确答案】 The inequality states that -5 is less than or equal
2、to x AND x must be less than 15 ( means “less than or equal to“ and means “less than“). Therefore, x could be any number between and including -5 and 15. 2 【正确答案】 Solve this problem algebraically, as follows: 6x-4x 5-(-3) 2x 8 x 4 x must be greater than 4 for this inequality to be true. 3 【正确答案】 The
3、 value of x is given, so substitute 7 for x and calculate the value of both sides: 3(7)+7=28 and 5(7)-6=29 The less than sign ( ) is used because 28 29. 4 【正确答案】 The first step in solving this problem is to isolate the variable on one side of the inequality: -5-20 -3x-2x -25 -5x 5 x It is important
4、to remember that when dealing with inequalities, multiplying or dividing by a negative number involves reversing the sign. In this case, both sides were divided by -5, so the sign changes from to . 5 【正确答案】 To solve this problem, subtract the 3 from both sides of the inequality: -4-3x 18-3 -7x 15 x is greater than or equal to -7, and it is less than 15.
