Question

1.2a+2a²+4a³ 2.5x³y-5xy 3.a²+b²+2ab

Answer 1

1、原式=2a（2a^2+a+1）

2、原式=5xy（x^2-1）=5xy(x+1)(x-1)

3、原式=(a+b)^2-4^2=(a+b+4)(a+b-4)

4、原式=4x(x^2-2x+1)=4x(x-1)^2

5、原式=(x^2+y^2-1)^2-(2xy)^2

=(x^2+y^2-1+2xy)(x^2+y^2-2xy-1)

=【(x-y)^2-1】【（x-y）^2-1】

=(x-y+1)(x-y-1)(x-y-1)(x-y+1)

=(x-y+1)^2(x-y-1)^2