1.若X^2(X+1)+y(xy+y)=(x+1)·A,则A=____?
问题描述：
1.若X^2(X+1)+y(xy+y)=(x+1)·A,则A=____?
2.已知x-y=1,xy=2,则x^3-2x^2y^2+xy^3的值是_____?
3.169(a+b)^2-121(a-b)^2
4.(x^2-2x)^2-14(x^2-2x)-15
5.(x+2)(x+4)+1
就这些了,都要分析步骤
答
1.A×(x+1)=(x^2+y^2)(x+1)
A=x^2+y^2
2.原式=xy(x^2-2xy+y^2)
=xy(x-y)^2
=2×1
=2
3.原式=(13a+13b)^2-(11a-11b)^2
=(13a+13b-11a+11b)(13a+13b+11a-11b)
=(2a+24b)(24a+2b)
=4(a+12b)(12a+b)
4.设x^2-2x=a
原式=a^2-14a-15
=(a-15)(a+1)
=(x^2-2x-15)(x^2-2x+1)
=(x-5)(x+3)(x-1)^2
5.原式=x^2+6x+8+1
=x^2+6x+9
=(x+3)^2
加分吧!累死我了啊!