定积分换元法是定积分计算的主要方法之一。
The method of the definite integral by substitution is one of the main techniques among the definite integral calculation.
第二类换元法是一种既重要又不易掌握的积分方法。
The second method of transformation is an important but not-easy-to-master calculus method.
用特定系数法、换元法、配方法探求二元二次函数的极值公式。
The extremal formula of binary quadratic functions is studied by using method of undetermined coefficients, substitution method and method of completing the square.
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