8x²-18y²-6x+9y
=2(4x²-9y²)-3(2x-3y) ---點解變左[-3y]既?
=2[(2x)²-(3y)²;]-3(2x-3y)
=2(2x+3y)(2x-3y)-3(2x-3y)
=(2x-3y)[2(2x+3y)-3]
=(2x-3y)(4x+6y-3)
收錄日期: 2021-04-12 18:13:18
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20061023000051KK02939