Math ws help !!

1.
A = sb + sc
s(b + c) = A
s= A/(b + c)


2.
cy - ax = bx
ax + bx = cy
x(a + b) = c
x = c/(a + b)


3.
a² = b² + 2c
(-10)² = (4)² + 2c
100 = 16 + 2c
2c = 84
c = 42


4.
v = u + at
(100) = (20) + (-2)t
-2t = 80
t = -40


5.
A=p(1+r/100)
題目不完整。


6.
左式
= 2(x + 7)
= 2x + 14
= (2x + 10) + 4
= 2(x + 5) + 4
= 右式


7.
左式
= 5(x - 4) - 7
= 5x - 20 - 7
= 5x - 27
= 右式


8.
(x - 1)(x + 4) = x² - Ax + B
x(x + 4) - (x + 4) = x² - Ax + B
x² + 4x - x - 4 = x² - Ax + B
x² + 3x - 4 = x² - Ax + B

比較兩邊 x 項：
-A = 3
A = -3

比較兩邊常數項：
B = -4


9.
4x² - 9y²
= (2x)² - (3y)²
= (2x + 3y)(2x -3y)


10.
49 - 4m²
= (7)² - (2m)²
= (7 + 2m)(7 - 2m)


11.
x² - 9
= x² - 3²
= (x + 3)(x - 3)


12.
4x² - 16
= 4(x² - 4)
= 4(x² - 2²)
= 4(x + 2)(x - 2)


13.
bx + cx + by + cy
= (bx + cx) + (by + cy)
= x(b + c) + y(b + c)
= (b+c)(x + y)


14.
ax + 3a + 6x + 18
= (ax + 3a) + (6x + 18)
= a(x + 3) + 6(x + 3)
= (x +3)(a + 6)


15.
3ax + ay - 3bx - by
= (3ax + ay) + (-3bx - by)
= a(3x + y) - b(3x + y)
= (3x+ y)(a - b)


16.
(-2q³/3p⁴)*(-9p/8q³)
= (-2/3)*(-9/8) * q³⁻³ * p¹⁻⁴
= (3/4) * p⁻³
= 3/(4p)


17.
1. 3cm 6cm 18.84cm 28.26cm²
2. 4cm 8cm 25.12cm 50.24cm²
3. 8cm 16cm 50.24cm 200.96cm²
4. 9cm 18cm 56.52cm 254.34cm²

2013-12-23 18:15:34 補充：
5.
A = P(1 + r/100)
110 = P(1 + 10/100)
1.1P = 110
P = 100 ... (ans)

To lin******@rocketmail.com :

你太忘的話，就抄 wanszeto 的答案好了。

事實也是如此！

1.s= A/(b + c)
2.x = c/(a + b)
3.c = 42
4.t = -40
5.題目不完整。
6.左=右
7.左=右
8. A = -3 B = -4
9. (2x + 3y)(2x -3y)
10. (7 + 2m)(7 - 2m)
11.(x + 3)(x - 3)
12.4(x + 2)(x - 2)
13. (b+c)(x + y)
14. (x +3)(a + 6)
15. (3x+ y)(a - b)
16. 3/(4p)
17.
1. 3cm(6cm)( 18.84cm) (28.26cm²)
2. (4cm) 8cm( 25.12cm)( 50.24cm²)
3.( 8cm )(16cm) 50.24cm (200.96cm²)
4.( 9cm )(18cm)( 56.52cm) 254.34cm²

太忙了，沒時間打列式，對不起

thx!!
NO.5

2013-12-25 21:58:16 補充：
!!!!!!!!!!!!!!!!!!!!!!
ok