標題:
發問:
1.John buys 2 lunch boxes and a glass of orange juice for $46.Mary buy 3 lunch boxes and 2 glasses of orange juicegor $74.Find the price of a lunch box and that of a glass of orange juice
最佳解答:
(1) Let the price of a lunch box be $x, and let the price of a glass of orange juice be $y. 2x+y=46---(1) 3x+2y=74---(2) (1)x3-(2)x2:-y=-10 y=10---(3) Sub (3) into (1): 2x+10=46 2x=36 x=18 Therefore x=18,y=10 Therefore the price of a lunch box is $18, the price of a glass of orange juice is $10. 2007-02-17 11:43:46 補充： method of subsititution:Let the price of a lunch box be $x, and let the price of a glass of orange juice be $y.2x十y=46---(1)3x十2y=74---(2)From (1),y=46-2x---(3)Sub (3) into (2):3x十2(46-2x)=743x十92-4x=74-x=-18x=18---(4)Sub (4) into (3):y=46-2(18)=46-36=10 2007-02-17 11:43:55 補充： Therefore x=18,y=10Therefore the price of a lunch box is $18, the price of a glass of orange juice is $10. 2007-02-17 11:46:26 補充： 以下又是另一種方法,但不知其名為何:Let the price of a lunch box be $x, and let the price of a glass of orange juice be $y.2x十y=46---(1)3x十2y=74---(2)From (1), y=46-2x---(3)From (2), y=(74-3x)/2---(4)Hence, 46-2x=(74-3x)/292-4x=74-3x-x=-18x=18---(5)Sub (5) into (3):y=46-2(18)=10
其他解答:
The prize of a lunch box is $18. The prize of a glass of orange juice is $10. I hope I can help you ! ^^|||||Let x be the price of lunch boxes Let y be the price of orange juice From John: 2x + y= 46 y = 46 - 2x From May: 3x + 2y = 74 Then join them together 3x + 2( 46 - 2x ) = 74 3x + 92 - 4x = 74 -x = -18 x=18 After we know x = 18 Then we can also know that 2x + y = 46 36 + y = 46 y = 8 Therefore the price of lunch boxes is $18 and the price of a glass of orange juice is $8|||||2x+y=46 ----------------(1) 3x+2y=74 ---------------(2) (1)x2 2(2x+y)=2(46) 4x+2y =92 ---------------(3) (3)-(2) 4x+2y=92 -)3x+2y=74 __________ x = 18 Put x = 18 into (3) 4x+2y =92 4(18)+2y =92 72+2y = 92 2y = 20 y =10 the price of a lunch box is 18 the price of glasses of orange juicegor is 10|||||let x be the price of a lunch box and y be the price of a glass of orange juice 2x + y = 46 --- 1 3x + 2y = 74 --- 2 1) y = 46 - 2x put 1 into 2 3x + 2(46 - 2x) = 74 3x + 92 - 4x = 74 -x + 92 = 74 18 = x x = 18 put x = 18 into 1 y = 46 - 2(18) = 46 - 36 = 10 so x = 18 and y = 10
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問1題數學題~發問:
1.John buys 2 lunch boxes and a glass of orange juice for $46.Mary buy 3 lunch boxes and 2 glasses of orange juicegor $74.Find the price of a lunch box and that of a glass of orange juice
最佳解答:
(1) Let the price of a lunch box be $x, and let the price of a glass of orange juice be $y. 2x+y=46---(1) 3x+2y=74---(2) (1)x3-(2)x2:-y=-10 y=10---(3) Sub (3) into (1): 2x+10=46 2x=36 x=18 Therefore x=18,y=10 Therefore the price of a lunch box is $18, the price of a glass of orange juice is $10. 2007-02-17 11:43:46 補充： method of subsititution:Let the price of a lunch box be $x, and let the price of a glass of orange juice be $y.2x十y=46---(1)3x十2y=74---(2)From (1),y=46-2x---(3)Sub (3) into (2):3x十2(46-2x)=743x十92-4x=74-x=-18x=18---(4)Sub (4) into (3):y=46-2(18)=46-36=10 2007-02-17 11:43:55 補充： Therefore x=18,y=10Therefore the price of a lunch box is $18, the price of a glass of orange juice is $10. 2007-02-17 11:46:26 補充： 以下又是另一種方法,但不知其名為何:Let the price of a lunch box be $x, and let the price of a glass of orange juice be $y.2x十y=46---(1)3x十2y=74---(2)From (1), y=46-2x---(3)From (2), y=(74-3x)/2---(4)Hence, 46-2x=(74-3x)/292-4x=74-3x-x=-18x=18---(5)Sub (5) into (3):y=46-2(18)=10
其他解答:
The prize of a lunch box is $18. The prize of a glass of orange juice is $10. I hope I can help you ! ^^|||||Let x be the price of lunch boxes Let y be the price of orange juice From John: 2x + y= 46 y = 46 - 2x From May: 3x + 2y = 74 Then join them together 3x + 2( 46 - 2x ) = 74 3x + 92 - 4x = 74 -x = -18 x=18 After we know x = 18 Then we can also know that 2x + y = 46 36 + y = 46 y = 8 Therefore the price of lunch boxes is $18 and the price of a glass of orange juice is $8|||||2x+y=46 ----------------(1) 3x+2y=74 ---------------(2) (1)x2 2(2x+y)=2(46) 4x+2y =92 ---------------(3) (3)-(2) 4x+2y=92 -)3x+2y=74 __________ x = 18 Put x = 18 into (3) 4x+2y =92 4(18)+2y =92 72+2y = 92 2y = 20 y =10 the price of a lunch box is 18 the price of glasses of orange juicegor is 10|||||let x be the price of a lunch box and y be the price of a glass of orange juice 2x + y = 46 --- 1 3x + 2y = 74 --- 2 1) y = 46 - 2x put 1 into 2 3x + 2(46 - 2x) = 74 3x + 92 - 4x = 74 -x + 92 = 74 18 = x x = 18 put x = 18 into 1 y = 46 - 2(18) = 46 - 36 = 10 so x = 18 and y = 10
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