Quadratic Equation(二次方程式的问题)let k be a constant,if A and B are the roots of the equation x^2 - 3x +k = 0,the A^2 + 3B = k 是恒数,如果A和B是x ^2 - 3x+ k= 0的根,A^2 + 3B =

Quadratic Equation(二次方程式的问题)let k be a constant,if A and B are the roots of the equation x^2 - 3x +k = 0,the A^2 + 3B = k 是恒数,如果A和B是x ^2 - 3x+ k= 0的根,A^2 + 3B =
Quadratic Equation(二次方程式的问题)
let k be a constant,if A and B are the roots of the equation x^2 - 3x +k = 0,the A^2 + 3B =
k 是恒数,如果A和B是x ^2 - 3x+ k= 0的根,A^2 + 3B =

Quadratic Equation(二次方程式的问题)let k be a constant,if A and B are the roots of the equation x^2 - 3x +k = 0,the A^2 + 3B = k 是恒数,如果A和B是x ^2 - 3x+ k= 0的根,A^2 + 3B =
因为A和B是x ^2 - 3x+ k= 0的两个根,所以A+B=3,即B=3-A
将B带入A^2 + 3B 原式转化为求A^2-3A+9的值
由A是x ^2 - 3x+ k= 0的根可知 A^2-3A= -k
所以原式=9-k