The extremal formula of binary quadratic functions is studied by using method of undetermined coefficients, substitution method and method of completing the square.
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。
2
By means of variable substitution and iterative method, this paper puts forth some new higher-order differential equations, and gives their formula of reduction of integrals to common denominator.