[數撚圍爐區] 全港最多數撚的POST上線啦 (31)

Analysis係要d時間build up個intuition, 做多d exercise有幫助
有d位你初學會完全唔覺有問題
例如你就咁話take identity Id from (0, 1]\S to [0, 1]\S我都可以問你點解Id係well-defined for this domain and codomain
(因為(0, 1]\S同[0, 1]\S直程係一樣, in general要define到identity from A to B你要A係subset of B)

Let f:R->R

f(x+f(y)+yf(x))=y+f(x)+xf(y) where x, y∈R

Find f(x)

有冇人識？