25a^4-769a^2+3600=0
问题描述:
25a^4-769a^2+3600=0
答
25a^4-769a^2+3600=(25a^4-600a^2+3600)-169a^2=(5a^2-60)^2-(13a)^2
=(5a^2-60+13a)(5a^2-60-13a)=(5a-12)(a+5)(5a+12)(a-5)=0
解得a=±5或者a=±12/5