Question

giúp e bài 40

Answer 1

40:

a: =(xy+1+x+y)(xy+1-x-y)

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

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

b: =(a+b)^2+2c(a+b)+c^2+(a+b)^2-2c(a+b)+c^2-4c^2

=2(a+b)^2-2c^2

=2[(a+b)^2-c^2]

=2(a+b+c)(a+b-c)

c: =(2ab-a^2-b^2+c^2)(2ab+a^2+b^2-c^2)

=[c^2-(a-b)^2][(a+b)^2-c^2]

=(c-a+b)(c+a-b)(a+b-c)(a+b+c)