(а+b)²(a-b)²=(a²+2ab+b²)(a²-2ab+b²)=a⁴-2a³b+a²b²+2a³b-4a²b²+2ab³+a²b²-2ab³+b⁴=a⁴-2a²b²+b⁴=(a²-b²)² (√5²-√2²)²=(5-2)²=3²=9
(а+b)²(a-b)²=(a²+2ab+b²)(a²-2ab+b²)=a⁴-2a³b+a²b²+2a³b-4a²b²+2ab³+a²b²-2ab³+b⁴=a⁴-2a²b²+b⁴=(a²-b²)² (√5²-√2²)²=(5-2)²=3²=9