[問題]GWD17-23

[balanana]

If 9x = 27y, which of the following expresses x in terms of y ?

A. 3^y
B. 3^(y - 1)
C. 3^(2y - 1)
D. 3^(2y - 3)
E. 3^(3y - 2)

Ans:E

我是算到3^2x=3^3y=(3^2*3^1)^y=3^2y*3^y
然後就不知道怎麼算出答案了
請誰好心指點一下好嗎?
thanks~

[medi66]

題目給的條件是9x = 27^y
所以 x=3^(3y)/ 9 = 3^(3y-2)