Question

从集合 $\{ -3, -2, -1, 4, 5 \}$ 中选出三个不同的数相乘，可能得到的最大乘积是

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

$10$

$20$

$30$

$40$

$60$

答案：C

知识点：最优化

难度评级：890

解答：

三个数的乘积要为正，要么三个全是正数，要么恰好两个是负数。这里只有两个正数，所以必须用两个负数和一个正数。

为了使乘积最大，取两个最小的负数和最大的正数： $(-3)(-2)(5) = 30$ 。

所以正确答案是 C。

For the product of three numbers to be positive, either all three are positive or exactly two are negative. There are only two positive numbers, so we must use two negatives and one positive.

To maximize, take the two most negative numbers and the largest positive: $(-3)(-2)(5) = 30$ .

Thus, the correct answer is C .

1990 AMC 8 第 7 题

答案：C

难度评级：890

解答：

其他年份的第 7 题