Integration: ∫3 dx - 3*∫dx

2006-10-20 11:56 am
Is the answer 0?
or 0 + C?
or something else...?

駛唔駛 "+C"?...
個答案好似係 0、因為 ∫3 dx = 3*∫dx
但唔+C又好似唔make sense...
更新1:

駛唔駛+C?... 個答案好似係 0、因為 ∫3 dx = 3*∫dx 但唔+C又好似唔make sense...

回答 (4)

2006-10-20 12:06 pm
✔ 最佳答案
∫3 dx - 3*∫dx

=∫3 dx - 3*∫1 dx

=3x+C1-3x-C2

=C1-C2

=C

應該加C



∫3 dx - 3*∫dx

=3*∫1 dx - 3*∫1 dx

=3(∫1 dx - ∫1 dx)

=3∫(1- 1) dx

=3C1

=C






2006-10-20 04:15:56 補充:
用文字說法就是因為不能肯定前面的常數等於後面的常數﹐相減後不能確定其值是0﹐所以要加C
2006-10-20 7:21 pm
∫3 dx - 3*∫dx



=∫3 dx - 3*∫1 dx



=3x+C1-3(x-C2) (where C1, C2 are arbitary constant)



=C1-3*C2



=C (since it is only an arbitary constant, we could change the variable)
參考: A maths textbook
2006-10-20 7:01 pm
∫3 dx - 3*∫dx



=∫3 dx - 3*∫1 dx



=3x+C1-3x-C2



=C1-C2



=C



應該加C







∫3 dx - 3*∫dx



=3*∫1 dx - 3*∫1 dx



=3(∫1 dx - ∫1 dx)



=3∫(1- 1) dx



=3C1



=C
參考: me
2006-10-20 12:09 pm
係要plus C架
因為如果work backwards
for eg C = 2,
d/dx 2 都係得返個零
所以唔可以排除非零既answer :D


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