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Linear Equations in Two Unknowns
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APPLICATIONS OF SIMULTANEOUS LINEAR EQUATIONS IN TWO UNKNOWS :1)The customer of an internet company has to pay a fixed cost plus an extra amount calculated according to the web- surfing time .if a customer spends 35hours for web-surfing,the payment is $173.if he spends 48hours for web-surfing,the payment... 顯示更多 APPLICATIONS OF SIMULTANEOUS LINEAR EQUATIONS IN TWO UNKNOWS : 1)The customer of an internet company has to pay a fixed cost plus an extra amount calculated according to the web- surfing time .if a customer spends 35hours for web-surfing,the payment is $173.if he spends 48hours for web-surfing,the payment is$212.find the fixed cost and the amount for web-surfuing per hour.
最佳解答:
1)The customer of an internet company has to pay a fixed cost plus an extra amount calculated according to the web- surfing time .if a customer spends 35 hours for web-surfing, the payment is $173.if he spends 48 hours for web-surfing, the payment is $212.Find the fixed cost and the amount for web-surfuing per hour. Let the fixed cost be $a, the amount for web-surfuing per hour be $b a + 35b = 173............(1) a + 48b = 212............(2) (2) - (1) : a + 48b - a - 35b = 212 - 173 13b = 39 b = 3 // Substitute b = 3 into (1) a + 35(3) = 173 a + 105 = 173 a = 68 // The fixed cost is $68, the amount for web-surfuing per hour is $3 2007-02-05 17:45:53 補充： 上述問題我用左 method of elimination~你亦可用method of substitution~a + 35b = 173............(1)a + 48b = 212............(2)From (1)a = 173 - 35b..............(3)Substitute (3) into (2)173 - 35b + 48b = 21213b = 39b = 3 // 2007-02-05 17:46:04 補充： Substitute b = 3 into (1)a 35(3) = 173a 105 = 173a = 68 //The fixed cost is $68, the amount for web-surfuing per hour is $3
其他解答:
Let x be the fixed cost and y be the amount for web-surfing per hour x+35y=173......(1) x+48y=212......(2) (2)-(1),(x+48y)-(x+35y)=212-173 x-x+48y-35y=39 13y=39 y=39/13 y=3 Sub y=3 into (1) x+35*3=173 x+105=173 x=173-105 x=68|||||let A =cost of surfing per hour B= fixed cost 35A+B =173 ------(1) 48A+B =212 ------(2) (from 1) => B=173-35A ------(3) substitute (3) into (2) =>48A+173-35A=212 13A=39 A=3 B=68C8D74AB62542840B
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