when u solve the equation x^2 = 49
u take (+ - ) square before them 不要問,只要信.[] 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?[] 覺得自己好失敗T^T 另類ans[]
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 ] 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... as up, how to show sqrt x is a function?
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