計算1/2(3a方-2ab+4b方)-2(3/4方-ab-3b方)

計算1/2(3a方-2ab+4b方)-2(3/4方-ab-3b方)

1/2(3a方-2ab+4b方)-2(3/4方-ab-3b方)
=3/2a方-ab+2b方-3/2a方+2ab+6b方
=ab+8b方
=b(a+8b)