因式分解:1、m^4+m^2-20 2、(m-n)^2-3(m-n)-40 3、(x-y)^2-4(x-y+15) 4、x^2(x^2-y^2)-72y^4
问题描述:
因式分解:1、m^4+m^2-20 2、(m-n)^2-3(m-n)-40 3、(x-y)^2-4(x-y+15) 4、x^2(x^2-y^2)-72y^4
^是平方的意思.
跪下了.
答
1、m^4+m^2-20 =(m-4)(m+5)2、(m-n)^2-3(m-n)-40 =(m-n+5)(m-n-8)3、(x-y)^2-4(x-y+15) =(x-y)^2-4(x-y)-60=(x-y+6)(x-y-10)4、x^2(x^2-y^2)-72y^4=x^4-x²y²-72y^4=(x²+8y²)(x²-9y²...