(a+b)²(a-b)²
=(a+b)(a-b)(a+b)(a-b)
=(a²-b²)(a²-b²)
=(a²-b²)²
=a⁴-2a²b² + b^4⁴
Σ( ° △ °|||)︴,如果度娘抽了的话,答案在这
(a+b)(a+b)(a-b)(a-b) = (a+b)(a-b)(a+b)(a-b) = (a^2-b^2)^2 = a^4 - 2(ab)^2 + b^4
(a+b)×(a-b)=[ (a+b)×(a-b)]=(a-b)=a^4-2ab+b^4