20分多題數學(因式分解)

1.r(p-2q)-(p-2q)
= (p-2q)(r-1)
2.c(a+b)^2 - b(a+b)^2
=(a+b)^2(c-b)
3.(a+b)h+(a+b)k
=(a+b)(h+k)
4.(c+d)m-(c+d)n
=(c+d)(m-n)
5.8(a+b)-(a-b)c
無得化簡.. 係唔係打錯正負?
6.2a(3p-q)-5b(3p-q)
=(3p-q)(2a-5b)
7.xy(s-t)+z(t-s)
=xy(s-t)-z(s-t)
= (s-t)(xy-z)
8.3d^2(u-2v)-7(2v-u)
= 3d^2(u-2v)+7(u-2v)
= (u-2v)(3d^2 +7)
9.am+an+mp+np
= a(m+n)+p(m+n)
=(a+p)(m+n)
10.5a+5b-ac-bc
=5(a+b)-c(a+b)
= (a+b)(5-c)
11.m+mn+1+n
=m(1+n)+(1+n)
=(m+1)(n+1)
12.at-bt+b-a
= t(a-b) - (a-b)
= (t-1)(a-b)
13.3cd-4c+28-21d
= c(3d-4)-7(3d-4)
= (3d-4)(c-7)
14.4x^2+3y+4xy+3x
= 4x^2+4xy+3y+3x
= 4x(x+y)+3(x+y)
= (x+y)(4x+3)
15.a^2-25
= (a+5)(a-5)

2010-09-18 01:22:47 補充：
5.8(a-b)-(a-b)c
= (8-c)(a-b)

1-6題果D其實都係抽同類項出黎..
比如第五題就係抽(a-b)出黎...
有d似乘法分配性質..

e.g : 3x17 + 2x17 = 17(3+2) = 85

2010-09-18 01:23:17 補充：
1-6本來無步驟@@ 基本上一定係直接出ans

8(a-b)-(a-b)c
(8-c)(a-b)

2010-09-17 18:49:40 補充：
其實本身有無步驟?
冇