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Emergency F.2 Simultaneous Linear Eauations in two Unknons
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發問:
The sum of both digits in a two-digit number is 13.When the digits are interchanged .the value of the number increases by 45. find the original number Need Details Method The sum of both in a two-digit number is 7 .If the number is less than 11 times the tens digit by 3.find the number Ned Details Method
最佳解答:
1. The sum of both digits in a two-digit number is 13.When the digits are interchanged .the value of the number increases by 45. find the original number Let the tens digit be a, units digit be b, the original number be ( 10a + b ) a + b = 13...............................(1) 10a + b + 45 = 10b + a.............(2) From (1), b = 13 - a.................................(3) From (2), 9a + 45 = 9b a + 5 = b..................................(4) Substitute (3) into (4) a + 5 = 13 - a 2a = 8 a = 4 // Substitute a = 4 into (4) b = 4 + 5 b = 9 // The original number is 49 . 2. The sum of both in a two-digit number is 7 .If the number is less than 11 times the tens digit by 3.find the number Let the tens digit be a, the units digit be b, number be ( 10a + b ) a + b = 7...............................(1) 10a + b + 3 = 11a...................(2) From (1), b = 7 - a..................................(3) From (2), a = b + 3 a - 3 = b..................................(4) Substitute (3) into (4) a - 3 = 7 - a 2a = 10 a = 5 // Substitute a = 2 into (3) b = 7 - 5 b = 2 // The number is 52
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