(5a²-2b²)²-(2a²-5b²)² 怎么算?

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(5a²-2b²)²-(2a²-5b²)² 怎么算?
(5a²-2b²)²-(2a²-5b²)² 怎么算?

(5a²-2b²)²-(2a²-5b²)² 怎么算?
(5a²-2b²)²-(2a²-5b²)²
=(5a²-2b²+2a²-5b²)(5a²-2b²-2a²+5b²)
=(7a²-7b²)(3a²+3b²)
=21(a²-b²)(a²+b²)
=21(a+b)(a-b)(a²+b²)
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(5a²-2b²)²-(2a²-5b²)²
=[ (5a²-2b²)+(2a²-5b²)][ (5a²-2b²)-(2a²-5b²)]
=(7a²-7b²)(3a²+3b²)
=21(a²-b²)(a²+b²)
=21(a-b)(a+b)(a²+b²)