Question

先化简，再求值：[(x-y)^2+(x+y)(x-y)]÷2x ，其中x=3,y=-2

先化简，再求值：[(x-y)^2+(x+y)(x-y)]÷2x ，其中x=3,y=-2
如题

Answer 1

原式=(x²-2xy+y²+x²-y²)÷2x
=(2x²-2xy)÷2x
=2x²÷2x-2xy÷2x
=x-y
=3-(-2)
=3+2
=5

Answer 2

先化简，再求值：[(x-y)^2+(x+y)(x-y)]÷2x ，其中x=3,y=-2
[(x-y)^2+(x+y)(x-y)]÷2x
=[(x-y)(x-y)+(x+y)(x-y)]÷2x
=[(x-y)(x+y+x-y)]÷2x
=[(x-y)(2x)]÷2x
=x-y
x-y=3-(-2)=3+2=5

Answer 3

[(x-y)^2+(x+y)(x-y)]÷2x ，其中x=3,y=-2
=(x^2-2xy+y^2+x^2-y^2)÷2x
=(2x^2-2xy)÷2x
=x-y
带入的5