第1个回答 2013-02-20
⑸3x²+[2x-﹙-5x²+4x﹚+2]-1
=3x²+[2x+5x²-4x+2]-1
=3x²+2x+5x²-4x+2-1
=8x²-2x+1
⑹﹙9a-2b﹚-[8a-﹙5b-2c﹚]+2c
=9a-2b-[8a-5b+2c]+2c
=9a-2b-8a+5b-2c+2c
=9a-2b-8a+5b-2c+2c
=a+3b
⑺4a²-[a²+﹙4a²-2a﹚-2﹙a²-3a﹚]
=4a²-[a²+4a²-2a-2a²+6a]
=4a²-[a²+4a²-2a-2a²+6a]
=4a²-a²-4a²+2a+2a²-6a
=a²-4a
⑻3/4 [4/3﹙1/3x-1﹚-8]-﹙-2/3x-5﹚
=3/4 [4/3﹙1/3x-1﹚-8]-﹙-2/3x-5﹚
=3/4 [4/3﹙1/3x-1﹚-8]+2/3x+5
=3/4 [4/3﹙1/3x-1﹚]-8*3/4+2/3x+5
=﹙1/3x-1﹚-6+2/3x+5
=x-2