若多项式x^2+2xy+ay^2-4=(x+y+2)(x+y-2)则a=?若多项式x^2-y^2+4x+M能够因式分解,写出一个符_数学解答

若多项式x^2+2xy+ay^2-4=(x+y+2)(x+y-2)则a=?若多项式x^2-y^2+4x+M能够因式分解,写出一个符合式子的M

人气：257 ℃　时间：2020-10-01 20:21:33

解答

若多项式x^2+2xy+ay^2-4=(x+y+2)(x+y-2)
(x+y+2)(x+y-2)=(x+y)^2-4=x^2+2xy+y^2-4 a=1
x^2-y^2+4x+M能够因式分解,
x^2-y^2+4x+M
=(x^2-y^2)+4x+M
=(x+y)(x-y)+4x+M M=4y
=(x+y)(x-y)+4(x+y)
=(x+y)(x-y+4)
所以M=4y