Question

已知A=x的平方-7x-2,B=-2x的平方+4x-1。求 2A-B/2

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Answer 1

2A-B/2
=2(x²-7x-2)-(-2x²+4x-1)/2
=2x²-14x-4+x²-2x+1/2
=3x²-16x-7/2

Answer 2

2A=2﹙x²-7x-2﹚
B/2=﹙-2x²+4x-1﹚÷2=-x²+2x-1/2
2A-B/2=3x²-16x-7/2