摘要:已知.A=a2+2b2-3c2.B= -b2-2c2+3a2.C=c2+2a2-3b2.求(A-B)+C.
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已知A=a2+b2-c2,B=-4a2+2b2+3c2,若A+B+C=0,则C是
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A.
5a2+3b2+2c2
B.
5a2-3b2+4c2
C.
3a2-3b2-2c2
D.
3a2+b2+4c2
已知A=3a2+b2-c2,B=-2a2-b2+3c2,且A+B+C=0,则C=
[ ]
A.a2+2c2
B.-a2-2c2
C.5a2+2b2-4c2
D.-5a2-2b2+4c2