taking into account as before that X^ is a function of

纳入考虑范围就像之前认为X^a
X^, you just get 100 - X^ now

是X^b的函数一样你得到了100-X^a
it's just going to be 30 - X^ times the derivative of

就会得到30-X^诚意X^a关于
X^ with respect to X^.

X^b的导数
Why is that?

为什么会这样呢
Because you know the chain rule, if I differentiate

因为链式法则如果我将所有的值
everything with respect to X^ and X^ is a function of X^

都区分为X^a是X^b的函数
it's just 30 because I'm taking the derivative with respect to x^.

那就会得到30 因为我会提取X^b的导数
So it's 30 times the derivative of X^ with respect to X^

那么就是X^a关于X^b的30倍
minus the derivative with respect to X^ is X^ tim157

减去X^a是X^b的函数的导数
the derivative of X^ with respect to X^,

X^a关于X^b的导数
so it's that.

就是这样