[問題]GWD 06-16

[spig]

What is the value of 3^-(x + y) / 3^-(x - y)?
(1) x = 2
(2) y = 3


ANS:B

不知道為什麼,一直解不出來,那位好心人士救一下我吧

謝謝

[iamger0730]

把y=3帶入，你會發現無論X的值是多少答案都一樣!

x=1 3^-4 / 3^2 = 3^-6

x=2 3^-5 / 3^1 = 3^-6

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以此類推啦~~~

希望有幫到你喔!!

[spig]

了解 大感謝

[65kevin]

What is the value of 3^-(x + y) / 3^-(x - y)?
(1) x = 2
(2) y = 3

另外提供一個想法供參考, 將題目的數學式化簡, 3^-(x + y) / 3^-(x - y) = [1/3^(x+y)] / [1/3^(x-y)] = 3^(x-y) / 3^(x+y) = 3^(-2y) , 所以只要知道 y 的值, 就可以得到答案, 和 x 無關, 所以選 (B)