(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 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)