2) (x+4y+5z)a
3) (a+2b)(2a+3b)
4) (5m+4n)(m-4n)
5) (3a+2b)(3a-2b)
6)Expand (1+x)(3-4x) and arrange the terms descending power of x.
*要有步驟!THX!
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更新1:
唔晒大家!>\/
更新2:
係唔該晒~ =]