Taking square roots

wisdoman

If x2 = 49
x = ± 7
But if x=√100
then
x=10


我想問sq.rt. 100 點解唔係± 10 ge...

sing2

原帖由 wisdoman 於 7-11-2008 08:10 發表
If x2 = 49
x = ± 7
But if x=√100
then
x=10


我想問sq.rt. 100 點解唔係± 10 ge...

我諗應該係你
x^2=49
所以先要
   x=±7
而你一開始就係
x=√100
就唔需要±
p.s 我的愚見

-終場ソ使者-

√100=±10
冇人話=+10 only- -

wilson1993912

我想問sq.rt. 100 點解唔係± 10 ge...

因為你計錯-.-

wisdoman

原帖由 -終場ソ使者- 於 7-11-2008 17:54 發表
√100=±10
冇人話=+10 only- -

原帖由 wilson1993912 於 7-11-2008 18:07 發表
我想問sq.rt. 100 點解唔係± 10 ge...

因為你計錯-.-

you mean √100=± 10 ?[[bao_26]] can you explain...

-終場ソ使者-

(-10)^2=100
(+10)^2=100
咁sqt100就係=+/-10

Zend

sqrt 100 = 10 only
我發現好多人9 up =.=...

lkhj2525

原帖由 -終場ソ使者- 於 7-11-2008 11:44 發表
(-10)^2=100
(+10)^2=100
咁sqt100就係=+/-10

√100 = 10
√-100 = √(-1)√(100) = 10i   ,i is a imaginary number which is learned in F.6~7
所以 √100 不會等於負數

[ 本帖最後由 lkhj2525 於 7-11-2008 12:47 編輯 ]

-終場ソ使者-

咁sqrt49都得姐

Zend

also the same =.=
in fact, this is a common mistake made by students [[tk_28]]