题目内容：

1:A^4-7A^2+1
2:(X-Y)(X-2Y)-6Y^2
3:(X^2+3X-3)(X^2+3X+4)
4:(X^2-7X+6)(X^2-X-6)+56
5:X^2-2XY-3Y^2+3X-5Y+2

优质解答

1.A^4-7A^2+1=a^4+2a^2+1-9a^2=(a^2+1)^2-9a^2=(a^2+3a+1)(a^2-3a+1)2.(X-Y)(X-2Y)-6Y^2=X^2-3XY-4Y^2=(X+Y)(X-4Y）3.（X^2+3X-3)(X^2+3X+4)-8=(x^2+3x)^2 -3(x^2+3x)+4(x^2+3x)-12-8=(x^2+3x)+(x^2+3x)-20=(x^2+3x+...