二元一次方程..計吾到.v.

若x= -8，求y

When x=-8,
1x/2-1=5y
-8/2-1=5y
-4-1=5y
-5=5y
y=-1

若y= -3，求x

When y=3,
5y=x/2-1
5(-3)=x/2-1
-15+1=x/2
-14*2=x
-28=x
i.e.x=-28

若x= -5 求y

When x=-5,
3x+2y-5=0
3(-5)+2y=0
-15+2y=0
2y=0+15
2y=15
y=15/2
y=7.5

若y=7，求x

When y=7,
3x+2y-5=0
3x+2(7)-5=0
3x+14=0+5
3x=5-14
3x=-9
x=-3

2010-06-30 16:00:47 補充：
Corr.2(a):

When x=-5,
3x+2y-5=0
3(-5)+2y=0+5
-15+2y=5
2y=5+15
2y=20
y=10

答 :

5y=2等於二分一x減一 即 5 y = 2 = x / 2 - 1

(a) 若x= -8，求y

5 y = x / 2 - 1

5 y = -8 / 2 - 1

5 y = - 4 - 1

5 y = - 5

y = - 1






(b) 若y= -3，求x

5 y = x / 2 - 1

5 ( - 3 ) = x / 2 - 1

- 1 5 = x / 2 - 1

- 1 4 = x / 2

- 7 = x

x = - 7







2. 3x+2y-5=0

(a) 若x= -5 求y

3 x + 2 y - 5 = 0

3 ( - 5 ) + 2 y - 5 = 0

- 1 5 + 2 y - 5 = 0

- 2 0 + 2 y = 0

2 y = 2 0

y = 1 0






(b) 若y=7，求x

3 x + 2 y - 5 = 0

3 x + 2 ( 7 ) - 5 = 0

3 x + 1 4 - 5 = 0

3 x + 9 = 0

3 x = - 9

x = - 3








希 望 可 以 幫 到 你 啦 . . ^ ^

中四教個個係一元二次方程...

Q.2
3x+2y=5=0

5 = 0??

2010-06-27 18:48:40 補充：
二元一次方程..計吾到.v.

5y = 2 = x/2 -1
(a)若x= -8，求y

A. When x = -8,
-8/2 -1 = 5y
-4-1 = 5y
5y = -5
y = -1

(b)若y= -3，求x

A. When y = -3,
5(-3) = x/2 -1
-15 = x/2 -1
x/2 = -14
x = -28

2. 3x+2y=5=0

5 = 0?

(a)若x= -5 求y

A. When x = -5,
3(-5)+2y = 5
-15+2y = 5
2y = 20
y = 10

or

When x = -5,
3(-5)+2y = 0
-15+2y = 0
2y = 15
y = 7.5

(b)若y=7，求x

A. When y = 7,
3x+2(7) = 5
3x+14 = 5
3x = -9
x = -3

or

When y = 7,
3x+2(7) = 0
3x+14 = 0
3x = -14
x = -14/3

2010-06-27 19:05:29 補充：
2. 3x+2y-5=0

(a)若x= -5 求y

A. When x = -5,
3(-5)+2y-5 = 0
-15+2y = 5
2y = 20
y = 10

(b)若y=7，求x

A. When y = 7,
3x+2(7)-5 = 0
3x+14 = 5
3x = -9
x = -3

里d咩方程?
我中4都未見過= =