a的x次方 求导过程不懂

复合函数中的链式法则ƒ(g(x))对x求导得ƒ'(g(x)) • g'(x)或dy/dx = dy/du • du/dx在这里,e^(xlna),令ƒ(u) = e^u,u = g(x) = xlnaƒ'(u) = e^u,g'(x) = lna则[ƒ(g(x))]' = ƒ'(u) • g'(x) = e^u • lna = e^(xlna) • lna = a^x • lna或令y = e^u,u = xlna则dy/du = e^u,du/dx = lna所以dy/dx = dy/du • du/dx = e^u • lna = e^(xlna) • lna = a^x • lna