Taking square roots

Zend

what I mean is

when u solve the equation x^2 = 49

u take (+ - ) square before them

[S]【YU】

不要問,只要信.[[tk_06]]

wisdoman

我ge理解係
x^2=100
x^2-100=0
(x-10)(x+10)=0
x=10 or x=-10

x=sqrt100         <-呢到ge x係+ve,同埋得一個解
x=10
Is it?[[tk_23]]

-終場ソ使者-

覺得自己好失敗T^T

piyopiyo

另類ans[[tk_32]]

sqrtx is a function
in a function,there cannot be "one to many"

[ 本帖最後由 piyopiyo 於 8-11-2008 10:47 編輯 ]

Zend

how to show sqrt x is a function

and your function is not well-defined.
As far as I know, u hvn't defined the set A and B of f:A->B...

[S]【YU】

as up, how to show sqrt x is a function?