若x+y=3,则x²-y²+6y=急

来源：学生作业帮助网编辑：六六作业网时间：2025/01/01 04:54:18

若x+y=3,则x²-y²+6y=急若x+y=3,则x²-y²+6y=急若x+y=3,则x²-y²+6y=急答：x+y=3x²-y

若x+y=3,则x²-y²+6y=急
若x+y=3,则x²-y²+6y=
急

若x+y=3,则x²-y²+6y=急
答：
x+y=3
x²-y²+6y
=(x-y)(x+y)+6y
=3(x-y)+6y
=3x-3y+6y
=3x+3y
=3(x+y)
=3*3
=9

x^2-y^2+6y=(x+y)(x-y)+6y=3(x-y)+6y=3x-3y+6y=3(x+y)=9