F.2Maths!!!!!!!!!!!40p!!!!!!

5.(a)
5xy - 8z - 10xz + 4y
= (5xy + 4y) + (-10xz - 8z)
= y(5x + 4) - 2z(5x + 4)
= (y - 2z)(5x + 4) ...... (answer)

5.(b)
6ra + sb - 2sa - 3rb
= (6ra - 2sa) + (-3rb + sb)
= 2a(3r - s) - b(3r - s)
= (2a - b)(3r - s) ...... (answer)

5.(c)
6am + 2nb - 4an - 3mb
= (6am - 3mb) + (-4an + 2nb)
= 3m(2a - b) - 2n(2a - b)
= (3m - 2n)(2a - b) ...... (answer)

5.(d)
3ax + 10by + 6bx + 5ay
= (3ax + 6bx) + (5ay + 10by)
= 3x(a + 2b) + 5y(a + 2b)
= (3x + 5y)(a + 2b) ...... (answer)

5.(e)
12ac + 7bd - 14bc - 6ad
= (12ac - 6ad) + (-14bc + 7bd)
= 6a(2c - d) - 7b(2c - d)
= (6a - 7b)(2c - d) ...... (answer)

5.(f)
ps - qt + sq - pt
= (ps + sq) + (-pt - qt)
= s(p + q) - t(p + q)
= (s - t)(p + q) ...... (answer)


6.(a)
cd³ - d²e - c²de + ce²
= (cd³ - d²e) + (-c²de + ce²)
= d²(cd - e) - ce(cd - e)
= (d² - ce)(cd - e) ...... (answer)

6.(b)
2p³ - 6q²t + 4pq² - 3p²t
= (2p³ + 4pq²) + (-3p²t - 6q²t)
= 2p(p² + 2q²) - 3t(p² + 2q²)
= (2p - 3t)(p² + 2q²) ...... (answer)

6.(c)
7m³ + mn² - 7m²n - n³
= (7m³ + mn²) + (-7m²n - n³)
= m(7m² + n²) - n(7m² + n²)
= (m - n)(7m² + n²) ...... (answer)

6.(d)
y³ - y² + y - 1
= (y³ - y²) + (y - 1)
= y²(y - 1) + 1(y - 1)
= (y² + 1)(y - 1) ...... (answer)

6.(e)
2b - 1 - 6ab² + 3ab
= (2b - 1) + (-6ab² + 3ab)
= 1(2b - 1) - 3ab(2b - 1)
= (1 - 3ab)(2b - 1) ...... (answer)

6.(f)
2a³ - 3b²c + 2ab² - 3a²c
= (2a³ + 2ab²) + (-3a²c -3b²c)
= 2a(a² + b²) - 3c(a² + b²)
= (2a - 3c)(a² + b²) ...... (answer)


7.
28x²y² + 5xy - 3
= 28x²y² + 12xy - 7xy - 3
= (28x²y² + 12xy) + (-7xy - 3)
= 4xy(7xy + 3) - 1(7xy + 3)
= (4xy - 1)(7xy + 3) ...... (answer)

5(a) 5xy − 8z − 10xz + 4y
5(y-2z)+4(y-2z)
(y-2z)(5+4y)

5(b) 6ra + sb − 2sa − 3rb
3r(2a-b)-s(2a-b)
(2a-b)(3r-s)

5(c) 6am + 2nb − 4an − 3mb
3m(2a-b)-2n(2a-b)
(3m-2n)(2a-b)

5(d) 3ax + 10by + 6bx + 5ay
3x(a+2b)+5y(a+2b)
(a+2b)(3x+5y)

5(e) 12ac + 7bd − 14bc − 6ad
6a(2c-d)-7b(2c-d)
(2c-d)(6a-7b)

5(f) ps − qt + sq − pt
p(s-t)+q(s-t)
(s-t)(p+q)

2009-10-01 23:06:59 補充：
6同7睇唔明 不過如果你明5其他應該都識!!

2009-10-01 23:11:07 補充：
第7之前以為錯了以家明了!!如下:
28x2y2+ 5xy − 3
=112xy+5xy-3
=xy(112+5)-3
=117xy-3
=3(99xy-1)

2009-10-02 09:23:37 補充：
樓下勵害!!難怪我不懂!!原來是次方!!我第7題也錯了