Question

（x+2）平方-（x-1）（x+1） 2. 3（-a+

Answer 1

（1）(x+2)²-(x-1)(x+1)=(x²+4x+4)-(x²-1)=4x+5

（2）(-a+1)(-a-1)-2(a+1)²=(a²-1)-2(a²+2a+1)=-a²-4a-3

（3）(2a+b)²-(-2a-b)²=(2a+b)²-(2a+b)²=0

（4）(x+y)²(x-y)²-(x-y)(x+y)(x²+y²)=[(x+y)(x-y)]²-(x²-y²)(x²+y²)

=(x²-y²)²-(x^4-y^4)

=x^4-2x²y²+y^4-x^4+y^4

=2y^4-2x²y²