因式分解,公式,要改正(form2)(20分)

①(a+b)^2-2a(a+b)+a^2
=((a+b)-a)^2
②16x^2-40xy+25y^2
=(4x-5y)^2
③(x^2-y^2)+2x-2y
=(x-y)((x+y)+2)
①q=2/rp-1/p主項變p
q=1/p(2/r-1)
p=2/rq-1/q
②1/a-1/b=3/b主項變b
1/a=4/b
b=4a
③y=z/10x-1/2x主項變x
y=(z-5)/10x
x=(z-5)/10y
④y=2x+3/x-1主項變x

2007-01-10 01:35:48 補充：
第4條要用quadratic equation ga!我form 4 先學,你應該打錯左呀~

2007-01-11 00:17:19 補充：
④y=(2x+3)/(x-1)主項變x xy-y=2s+3 xy-2x=y+3 x(y-2)=y+3 x=(y+3)/(y-2)

①(a+b)²-2a(a+b)+a²

=a²+b²+2ab-2a²-2ab+a²

=b²
-------------------------------------------------------------------------------------------------------
②16x²-40xy+25y²

=(4x-5y)²
-------------------------------------------------------------------------------------------------------
③(x²-y²)+2x-2y

=(x+y)(x-y)+2(x-y)

=(x - y)(x + y + 2)
=========================================================
①q=2/pr-1/p [p]

q=(2-r)/pr

pqr=2-r

p=(2-r)/qr
-------------------------------------------------------------------------------------------------------
②1/a-1/b=3/b [b]

(b-a)/ab=3/b

b-a=3a

b=4a
-------------------------------------------------------------------------------------------------------
③y=z/10x-1/2x [x]

y=(z-5)/10x

10xy=z-5

x=(z-5)/10y
-------------------------------------------------------------------------------------------------------
④y=(2x+3)/(x-1) [x]

xy-y=2x+3

xy-2x=3+y

x(y-2)=3+y

x=(3+y)/(y-2)

①(a+b)^2-2a(a+b)+a^2
=((a+b)-a)^2
②16x^2-40xy+25y^2
=(4x-5y)^2
③(x^2-y^2)+2x-2y
=(x-y)((x+y)+2)
①q=2/rp-1/p主項變p
q=1/p(2/r-1)
p=2/rq-1/q
②1/a-1/b=3/b主項變b
1/a=4/b
b=4a
③y=z/10x-1/2x主項變x
y=(z-5)/10x
x=(z-5)/10y
④y=2x+3/x-1主項變x

1.(a+b)^2-2a(a+b)+a^2
by (a-b)^2=a^2-2ab+b^2,and we treat (a+b)^2 as one term we get
=[(a+b)-a]^2
=[b]^2
2.16x^2-40xy+25y^2
=(4x)^2-40xy+(5y)^2
=[(4x)-(5y)]^2
3.(x^2-y^2)+2x-2y
=(x^2-y^2)+2(x-y)
=(x+y)(x-y)+2(x-y)
=(x-y)[(x+y)+2]
4.q=2/rp-1/p
q=2/rp-r/rp
q=(2-r)/rp
rpq=2-r
p=(2-r)/rq
5.1/a-1/b=3/b
1/a=3/b+1/b
1/a=4/b
b(1/a)=4
b=4a
6. y=z/10x-1/2x
y=z/10x-5/10x
y=(z-5)/10x
10xy=z-5
x=(z-5)/10y
7. y=2x+3/x-1
y(x-1)=2x+3
xy-y=2x+3
xy-2x-y=3
x(y-2)-y=3
x(y-2)=3+y
x=(3+y)/(y-2)

2007-01-10 13:43:08 補充：
我想講ge係第1個人ge Q.1都未factorize 哂,應該要factorize到得番b^2先啱而bird,我想話將d野group番埋佢咪即係factorize lor,expand 先係將d野乘開哂佢,所以Q.2唔係冇得做ga

(a+b)^2 - 2a(a+b) + a^2
(a+b)(a+b-2a) + a^2
(a+b)(b-a) + a^2
-(a+b)(a-b) + a^2
-(a^2-b^2) + a^2
-a^2 + b^2 + a^2
b^2

16x^2 - 40xy + 25y^2
(4x)^2 - 2(4x) + (5y)^2
(4x-5y)^2

(x^2-y^2) + 2x - 2y
(x+y)(x-y) + 2x - 2y
(x+y)(x-y) +2(x-y)
(x-y)(x+y+2)

q = 2/rp - 1/p
qp = 2/r - 1
p = 2/qr - 1/q

1/a - 1/b = 3/b
1/a = 3/b + 1/b
1/a = 4/b
b = 4a

y = z/10x - 1/2x
y = (z-5)/10x
10xy = z-5
x = (z-5)/10y

y = (2x+3)/(x-1)
(x-1)y = 2x+3
xy-y = 2x+3
xy-2x = y+3
x(y-2) = y+3
x = (y+3)/(y-2)

最後果條我唔係好清楚條問題點問...
所以我估你打少左d括號...
希望答倒你啦

1. (a+b)^2-2a(a+b)+a^2
= a^2 + 2ab + b^2 - 2a^2 - 2ab + a^2
= b^2

2. 16x^2-40xy+25y^2
= 因式分解!? 冇得分 gor lor wor? 如果想 group 返埋的話就係咁...
= (4x - 5y)^2

3. (x^2-y^2)+2x-2y
= (x + y)(x - y) + 2(x - y)
= (x - y)(x + y + 2)

1. q=2/rp-1/p
q = 2/rp - r/rp
q = (2-r)/rp
p = qr/(2-r)

2. 1/a-1/b=3/b主項變b
1/a = 3/b + 1/b
1/a = 4/b
b = 4a

3. y=z/10x-1/2x主項變x
y = z/10x - 5/10x
y = (z-5)/10x
x = 10y/(z-5)

4. y=2x+3/x-1
你肯定條題目係咁? 而唔係 y = (2x+3) / (x-1)??
因為據你咁寫, 就變左 quadratic 了.... 即係有 2 個答案的.... 我唔知 f.2 學左呢 d 未喎..... 一係你補充下, 我轉頭再答埋啦~

2007-01-10 01:41:48 補充：
如果真係 y = (2x 3) / (x-1) 的話...y (x-1) = 2x 3yx - y = 2x 3-y - 3 = 2x - yx-y - 3 = x (2-y)x = -(y 3)/(2-y)