代數20分！！！！！！！！！

(1) 3a+6
=3(a+2)
(2) 2m-4n
=2(m-2n)
(3) 3p+2g+12r
+) 2a+8 +) -7+3n +) 4p-2g-7r
=(3p+4p)+(2g-2g)+(12r-7r)+2a+3n+(8-7)
=7p+5r+2a+3n+1

(a)4a+3b-2c-7a-2b+9c
=(4a-7a)+(3b-2b)+(9c-2c)
=b-3a+7c

(b) -3m-7n+4+m-2n-4
=(-3m+m)+(-7n-2n)+(4-4)
= -2m-9n

首先....教你一個好記既方法
將同一個terms 既野group埋一齊~
e.g. 3m ,2m 佢地就係同一個terms,因為共同有m term~
將佢加減~

跟住睇下有冇最小公倍數出來~
e.g. 3n+6m.....3就係最少公倍數
所以 3(n+2m)
e.g 6q+2p ....2就係最少公倍數
所以2(p+3q)

2007-09-01 18:10:59 補充：
sorry...1,2,3答案係.....(1) 3a+6 (2) 2m-4n (3) 3p+2g+12r+) 2a+8 +) -7+3n +) 4p-2g-7r1) 5a+142) -n+2m-73) 7p +5r都係同一個terms......將佢加減先~好似第一題......一個3a,一個2a......同一類既野~就加埋一齊~

2007-09-01 18:13:15 補充：
其實好易睇~你唔好怕個d英文字母~3m 2m....唔使理個m.....但係要知佢地要加埋一齊~=5m5n 2n...唔使理個個n.....=7n好似加減數咁~只不過同7 2..有少少分別....只係佢加多左個英文字母係後面,當裝飾lor~^^

2007-09-01 18:14:24 補充：
其實好易睇~你唔好怕個d英文字母~3m 2m....唔使理個m.....但係要知佢地要加埋一齊~=5m5n 2n...唔使理個個n.....=7n好似加減數咁~只不過同7 2..有少少分別....只係佢加多左個英文字母係後面,當裝飾lor~^^

(1)
(3a+6)+(2a+8)
=3a+6+2a+8
=(3a+2a)+(6+8)
=5a+14

(2)
(2m-4n)+(-7+3n)
=2m-4n-7+3n
=2m+(3n-4n)-7
=2m-n-7

(3)
(3p+2g+12r)+(4p-2g-7r)
=3p+2g+12r+4p-2g-7r
=(3p+4p)+(2g-2g)+(12r-7r)
=7p+5r

(a)
4a+3b-2c-7a-2b+9c
=(4a-7a)+(3b-2b)+(9c-2c)
=-3a+b+7c

(b)
-3m-7n+4+m-2n-4
=(-3m+m)+(-7n-2n)+(4-4)
=-2m-9n

(1) 5a+14
(2)2m-1n-7
(3)7p+5r
(a)-3a+b+7c
(b)-1m-9n

2007-09-01 18:05:32 補充：
(B) -2m-9n先o岩