Question

已知(x+ax)(x+by)=x的二次方-4xy+6y的二次方,求代数式3(a+b)-2ab

Answer 1

(x+ay)(x+by)=x的二次方-4xy+6y^2

x^2+(a+b)xy+aby^2=x^2-4xy+6y^2

a+b=-4

ab=6

3(a+b)-2ab=3*(-4)-2*6=-24