Series F is defined as F n = F(n – 1) + 3 and F 1 = 10

题目

Series F is defined as F n = F(n – 1) + 3 and F 1 = 10.

Quantity A

The sum of F 4 through F 10

Quantity B

The sum of F 6 through F 11

选项

Quantity A is greater.

Quantity B is greater.

The two quantities are equal.

The relationship cannot be determined from the information given.

解析

该数列为等差数列，每一项都等于前一项加3。此外，我们可以发现两列有很多相同项，因为： A列：F4+F5+F6+F7+F8+F9+F10 B列：F6+F7+F8+F9+F10+F11 因此，我们可以将比较简化为： A列：F4+F5 B列：F11 由于每一项都比前一项大3，我们可以计算这三项的值： F4 = F1 + 3×3 = 19；F5 = F4 + 3 = 21；F11 = F5 + 6×3 = 39。此时，A列 = 19 + 21 = 40，B列 = 39。 A列的数值更大！

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