Ia-bI-I2c-bI+Ia-cI绝对值问题,帮帮忙,C

Ia-bI-I2c-bI+Ia-cI绝对值问题,帮帮忙,C
Ia-bI-I2c-bI+Ia-cI绝对值问题,帮帮忙,C

Ia-bI-I2c-bI+Ia-cI绝对值问题,帮帮忙,C
因为A0,所以Ia-cI=a-c
原式=b-a+b-2c+a-c=2b-3c

∵c∴a-b<0,2c-b<0,a-c>0,
∴Ia-bI-I2c-bI+Ia-cI
=b-a+2c-b+a-c
=c.

∵C﹤A﹤0﹤B
∴A-B﹤0,2C-B﹤0,A-C﹥0
∴▏A-B▏-▏2C-B▏+▏A-C▏
=-(A-B)-[-(2c-b)]+A-C
=-A+B+2C-B+A-C
=C