Jawapan

2015-09-05T00:01:05+08:00
(3a+b)(c+2d) = 3ac + 6ad + bc + 2bd
2015-09-05T00:10:19+08:00
= 3a × c = 3ac
= 3a × 2d = 6ad
= b × c = bc
= b × 2d = 2bd

= 3ac + 6ad + bc + 2bd