wxf2006
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(a^2-6a+5)(a^2+6a+5)-a^2(a^2-4)
=[(a^2+5)-6a][(a^2+5)+6a]-a^2(a^2-4)
=(a^2+5)^2-36a^2-a^4+4a^2
=(a^2+5)^2-32a^2-a^4
=a^4+10a^2+25-32a^2-a^4
=a^4-a^4+10a^2-32a^2+25
=-22a^2+25
=-22*(-2/11)^2+25
=-22*4/11*11+25
=-2*4/11+25
=-8/11+25
=267/11
1年前
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