s20945

          quesion 2 please,感激萬分

nicolekw

答案係咪D牙..

s20945

yes,我唔識計--

nicolekw

可以代數..
代 k = 4

[ 本帖最後由 nicolekw 於 2011-4-25 06:59 PM 編輯 ]

s20945

能有詳盡的step 4 嗎

nicolekw

step 就冇..
但係我可以解釋比你知..
x - k < 0    --> x < k
&佢話 x < 4
所以k > 4
而當你唔肯定 k 係咪 = 4
可以代數去驗證

[ 本帖最後由 nicolekw 於 2011-4-23 09:24 PM 編輯 ]

firoazen

咁如果唔係mc呢? = =

nicolekw

我會skip左個step..
直接寫答案 = =

桃子

From the 1st inequality, x<4.
From the 2nd inequality, x<k.

If the solution is x<4, then we need k>=4.

nicolekw

可以就咁寫？
我覺得始終好似冇咩解釋到點解 k = 4

桃子

引用:

原帖由 nicolekw 於 2011-4-23 09:36 PM 發表
可以就咁寫？
我覺得始終好似冇咩解釋到點解 k = 4

"x<4 and x<4" is equivalent to x<4

That's why k=4 is accepted.

s20945

then can we solve it by graph?

桃子

I don't think so.

nicolekw

睇唔明你句野..= =
"x<4 and x<4" is equivalent to x<4

我明白點解 k = 4
但我唔識去表達...
-------------------------------
我唔同意你既表達方式..
我知
From the 1st inequality, x<4.
From the 2nd inequality, x<k.
但點解If the solution is x<4, then we need k>=4.
你冇解釋到
That's why 我話唔識寫step..
因為我寫唔出

[ 本帖最後由 nicolekw 於 2011-4-24 12:00 AM 編輯 ]

桃子

It's intuitive.

If k<4, then
"x<4 and x<k" is equivalent to x<k.

If k>=4, then
"x<4 and x<k" is equivalent to x<4.