2021 SPRING AMC12A 真题

2021Spring AMC 12A

Problem 1

下式的值是多少

Problem 2

Under what conditions does hold, where and are real numbers?

• (A) It is never true. ｜永远不成立。
• (B) It is true if and only if ab =0. ｜当且仅当 ab =0 时才成立。
• (C) It is true if and a + b ≥ ｜当且仅当 0. a + b ≥ 时才成立。 0
• (D) It is true if and only if ab =0 and a + b ≥ 0. | 当且仅当 ab =0 且 ＋ ≥ 时时才成立。 a b 0
• (E) It is always true. ｜总是成立。

Problem 3

The sum of two natural numbers is . One of the two numbers is divisible by . If the units digit of that number is erased, the other number is obtained. What is the difference of these two numbers?

两个自然数之和是 17,402 。这两个数中的一个可以被 10 整除。如果去掉该数的个位数字则得 到另外一个数。问这两个数的差是多少？

(A) 10,272 (B) 11,700 (C) 13,362 (D) 14,238 (E) 15,426