计算:(3a-5b-2c)(-3a-5b+2c)简便算法需过程.

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计算:(3a-5b-2c)(-3a-5b+2c)简便算法需过程.

计算:(3a-5b-2c)(-3a-5b+2c)简便算法需过程.
计算:(3a-5b-2c)(-3a-5b+2c)
简便算法需过程.

计算:(3a-5b-2c)(-3a-5b+2c)简便算法需过程.
(3a-5b-2c)(-3a-5b+2c)
=[(3a-2c)-5b][(-(3a-2c)-5b]
=-[(3a-2c)-5b][(3a-2c)+5b]
=-(3a-2c)^2+(5b)^2
=-9a^2-4c^2+12ac+25b^2
吉林 汪清LLX

(3a-5b-2c)(-3a-5b+2c)
=[-5b+(3a-2c)][-5b-(3a-2c)]
=(-5b)^2-(3a-2c)^2
=25b^2-9a^2+12ac-4c^2

1.在第2个括号里提个负号,原式=-(3a-2c-5b)×(3a-2c+5b)=-[(3a-2c)-5b]×[(3a-2b)+5b]=-[(3a-2c)^2-25b^2] =-9a^2+12ac-4c^2+25b^2