數學抽數和英文文法問題

2011-08-25 8:10 pm
2^x - 2 ^ (3-x) = 7
2^x - (8)/(2^x) = 7
問題一
我想問點樣抽2^x 出黎?

問題二: Hotels try to make visitors feel at home
點解以上一句有2個verbs?

回答 (1)

2011-08-25 9:10 pm
✔ 最佳答案
Q1.

2^x-2^(3-x)=7

mutiply the equation by 2^x, we have
2^2x-8=7.2^x

let 2^x be y, we have
y^2-8=7y
y^2-7y-8=0
(y-8)(y+1)=0
y=8 or y=-1(rejected)

therefore 2^x=8
x=log8/log2

Q2.
Hotels try to make visitors feel at home

其實這句只有一個動詞try
至於to make是不定詞(to-infinitive)

而make之後我們可以再用原型動詞,如:
It made me cry(cry就是原形動詞)

因此,句中的feel也是原形動詞(bare infinitive)

希望幫到你!


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