AMC8 1990

AMC8 1990 · Q7

AMC8 1990 · Q7. It mainly tests Word problems (algebra), Logic puzzles.

When three different numbers from the set $\{-3, -2, -1, 4, 5\}$ are multiplied, the largest possible product is

从集合 $\{-3, -2, -1, 4, 5\}$ 中选取三个不同的数相乘，最大可能积是

(A) 10 10

(B) 20 20

(D) 40 40

(E) 60 60

Answer

Correct choice: (C)

正确答案：（C）

Solution

For the product of three numbers to be positive, either all three must be positive or two negative and one positive. Since there are only two positives, the max is $(-3)(-2)(5)=30$.

三个数的乘积为正，要么全正，要么两个负一个正。由于只有两个正数，最大值为 $(-3)(-2)(5)=30$。

Topics