已知A=(a+2)(a-2),B=2(6-1/2a²),C=(a-1)²,化简3A+2B-C

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已知A=(a+2)(a-2),B=2(6-1/2a²),C=(a-1)²,化简3A+2B-C已知A=(a+2)(a-2),B=2(6-1/2a²),C=(a-1)

已知A=(a+2)(a-2),B=2(6-1/2a²),C=(a-1)²,化简3A+2B-C
已知A=(a+2)(a-2),B=2(6-1/2a²),C=(a-1)²,化简3A+2B-C

已知A=(a+2)(a-2),B=2(6-1/2a²),C=(a-1)²,化简3A+2B-C

3A+2B-C
=3(a+2)(a-2)+4(6-1/2a²)-(a-1)²
=3(a²-4)+24-2a²-(a²-2a+1)
=(3a²-2a²-a²)+2a+(-12+24-1)
=2a+11

A=a²-4
B=12-a²
C=a²-2a+1
所以原式=3a²-12+24-2a²-a²+2a-1
=2a+11

3A+2B-C
=3(a+2)(a-2)+2×2(6-1/2a²)-(a-1)²
=3a²-12+24-2a²-a²+2a-1
=2a+11