计算:(3a-b+c)(3a-b-c)+(3a+b)²和(a-m+n)²

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计算:(3a-b+c)(3a-b-c)+(3a+b)²和(a-m+n)²
计算:(3a-b+c)(3a-b-c)+(3a+b)²和(a-m+n)²

计算:(3a-b+c)(3a-b-c)+(3a+b)²和(a-m+n)²
(3a-b+c)(3a-b-c)+(3a+b)²
=[3a+(b+c)][3a-(b+c)]+(3a+b)²
=9a²-(b-c)²+(3a+b)²
=9a²-b²+2bc-c²+9a²+6ab+b²
=18a²-c²+6ab+2bc
(a-m+n)²
=[(a-m)+n]^2
=(a-m)^2+2n(a-m)+n^2
=a^2-2am+m^2+2an-2mn+n^2