GRE考试

【单选题】For any numbers a, b, and c,

For which of the following equations is it true that there is exactly one positive integer that satisfies it’

A、none
B、Ⅰ only
C、Ⅲ only
D、Ⅰ and Ⅲ only
E、Ⅰ, Ⅱ, and Ⅲ
网考网参考答案：C
网考网解析：
Check each choice to see which equation has exactly one positive integer solution. Ⅰ. For every number a: (0)(a)(-a) = 0 and 0 + a + (-a) = 0, so for every positive integer a, [*] Ⅱ. [*] We’re looking for positive solutions, so assume a ≠ 0, and divide by a: [*] But [*] is not an integer. (Ⅱ is false.) Ⅲ. [*] a 2 = 1. This equation has one positive integer solution, a = 1. (Ⅲ is true.) Statement Ⅲ only is true. document.getElementById("warp").style.display="none"; document.getElementById("content").style.display="block"; 查看试题解析出处>>