7-2y/4 = 2y+3. what is 'y'?

2010-01-22 11:53 am

回答 (6)

2010-01-22 1:38 pm
✔ 最佳答案
(7 - 2y)/4 = 2y + 3
7 - 2y = 4(2y + 3)
7 - 2y = 4(2y) + 4(3)
7 - 2y = 8y + 12
-8y - 2y = -7 + 12
-10y = 15
y = 15/(-10)
y = -3/2 (-1.5)
2010-01-22 8:48 pm
I suspect that question has been incorrectly presented and SHOULD be shown as :-

( 7 - 2 y ) / 4 = 2 y + 3

7 - 2 y = 8 y + 12
- 5 = 10 y
y = - 1 / 2
2010-01-22 8:17 pm
If you meant 7 - 2y/4 = 2y +3
then
-2y/4 - 2y = 3 - 7
(-2y - 8y) / 4 = -4
-2y - 8y = 4(-4)
-10y = -16
y = -16/-10
y = 8/5 or y = 1.6

If you meant (7 - 2y) / 4 = 2y + 3
then
7 - 2y = 4(2y + 3)
7 - 2y = 8y + 12
-2y - 8y = 12 - 7
-10y = 5
y = 5/-10
y = -1/2 or y = -0.5
參考: My brain. :)
2010-01-22 8:04 pm
7-2y/4=2y+3
(28-2y)/4=2y + 3 LCD
28-2y=8y+12 cross multiplication
28-12=8y+2y transposition
16=10y
y= 8/5
2010-01-22 8:01 pm
7-2y/4 = 2y+3
=> 7-3 = 2y + 2y/4
=> 4 = 1/4( 8y + 2y)
=> 16 = 10y
=> y = 1.6
2010-01-22 8:01 pm
(7-2y)/4 = 2y+3
7-2y = 4(2y+3)
7-2y = 8y+12
7-12 = 8y+2y
-5 = 10y
y = -5/10

therefore y = -1/2 (y = -0.5)


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