A condition expression.

一个条件表达式。

youdao

Specifies an additional search condition expression for the data column, linked to previous expressions with a logical OR.

指定数据列的附加搜索条件表达式，并用逻辑 OR 链接到先前的表达式。

youdao

youdao

So we can now take this expression and rewrite it under the condition of du is equal to zero.

我们利用这个公式,并在du=0的条件下将它重写。

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I differentiate a second time and check the sign, so the second order condition, I differentiate this expression again with respect to q1.

我们对它进行二次求导然后看符号,这个式子的二阶导数,就是一阶导数再对q1进行求导

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