论文部分内容阅读
在学习二次函数时,经常遇到由已知的三对自变量的值和对应的函数值,求二次函数的解析式.如果用二次函数的一般形式y=ax~2+bx+c就需要解一个三元一次方程组,当所给出的这三对自变量的值和对应的函数值一般情形时,解对应的三元一次方程组是较麻烦的,而如果用下面的定理就可以避免解三元一次方程组,直接求出二次函数的解析式.定理已知一个二次函数当x=a时,y
When learning the quadratic function, it is often encountered to find the analytical solution of the quadratic function from the known values of the three pairs of independent variables and the corresponding function values. If we use the general form of the quadratic function y = ax ~ 2 + bx + c need to solve a ternary system of equations, given the values of the three pairs of arguments and the corresponding general case of function values, solving the corresponding ternary system of equations is more troublesome, and if we use the following theorem We can avoid the solution of the ternary system of equations and get the analytic formula of the quadratic function directly. Theorem Given a quadratic function When x = a, y