～兩題中一數學題目～

1) (2^16 X 5^25) / (5^24 X 2^14)
= 2^(16 - 14) X 5^(25 - 24)　　　　　∵ a^m/a^n = a^(m - n)
= 2^2 X 5
= 4 X 5
= 20

2) (y+1)^2 (y-3)
= (y^2 + 2y + 1)(y - 3)　　　　　∵ (a + b)^2 = a^2 + 2ab + b^2
= y^3 + 2y^2 + y - 3y^2 - 6y - 3
= y^3 - y^2 - 5y - 3

2007-01-07 21:51:24 補充：
(y + 1)^2 = (y^2 + 2y + 1) 此乃一項公式公式為(a + b)^2 = a^2 + 2ab + b^2如果唔識就自行乘散佢　(y + 1)^2 (y-3)= (y + 1)(y + 1)(y-3)= (y^2 + y + y + 1)(y - 3)= (y^2 + 2y + 1)(y - 3)= y^3 + 2y^2 + y - 3y^2 - 6y - 3= y^3 - y^2 - 5y - 3

1. Simplify簡化. 上與下約. 2^2×5 = 4×5 = 20
2. Expand展開.
(y^2×2y×1)(y-3)
=y^3 + 2y^2 + y - 3y^2 - 6y - 3
=y^3 - y^2 - 5y - 3

2007-01-07 22:19:30 補充：
其實, F.2你會學到3條叫identities的東西. 1. (a+b)^2 = a^2 + 2ab + b^22. (a-b)^2 = a^2 - 2ab + b^23. (a+b)(a-b) = a^2 - b^2如題, (y+1)^2 = y^2 + 2y + 1因此, (y-3)(y^2 + 2y + 1)= y^3 + 2y^2 + y - 3y^2 - 6y - 3= y^3 - y^2 - 5y - 3

2007-01-07 22:52:10 補充：
你中一唔識, 就只好拆散佢乘, 即係我原先的回答.

1)
不准便用計數機，化簡下列表達式
　216 X 525
──────
　524 X 214

=216-14 X 5 25-24
=22 X 5
= 4 X 5
= 20

2)
展開下列表達式
(y+1)2 (y-3)
= (y2 + 2y + 1)(y – 3)
= y(y2 + 2y + 1) - 3(y2 + 2y + 1)
= y3 + 2y2 + y - 3y2 - 6y – 3
= y3 - y2 - 5y – 3

1)上同下約...
2^2x5
=20

2)......(y+1)^2 (y-3)???成舊???定中間有加號ga?
(y^2+2y+1)(y-3)
y^3+2y^2+y-3y^2-6y-3
y^3-y^2-5y-3

2007-01-07 22:06:32 補充：
我明lu~~~咁呢個answer arm ga la你既意思係兩個相乘吧(y+1)^2=(y+1)(y+1)成條應該係(y+1)(y+1)(y-3)一個個計就ok ga la

2007-01-07 23:59:06 補充：
(y+1)(y+1)(y-3)<---呢個你明嗎??之後(y+1)(y+1) (y-3)<---先計頭2個y*y+y+y+1=y^2+2y+1(y^2+2y+1)(y-3)<---呢度ok未???y^2*y+2y*y+y-3y^2-6y-3y^3+2y^2+y-3y^2-6y-3y^3-y^2-5y-3明晒未??唔明可以再問我