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標題:
simultaneous equation
發問:
the sum of the two digits of a two-digit number is 9. If the digits are reversed, the number will be increased by 45. find the original number
最佳解答:
Let a and b be the tens digit and the unit digit respectively. a + b = 9 ...... (1) (10b + a) - (10a + b) = 45 ...... (2) (2): 10b + a - 10a - b = 45 -9a + 9b = 45 -a + b = 5 ...... (3) (1)+(3): 2b = 14 b = 7 Put b = 7 into (1): a + (7) = 9 a = 2 Ans: The original number is 27. =
其他解答:
simultaneous equation
發問:
the sum of the two digits of a two-digit number is 9. If the digits are reversed, the number will be increased by 45. find the original number
最佳解答:
Let a and b be the tens digit and the unit digit respectively. a + b = 9 ...... (1) (10b + a) - (10a + b) = 45 ...... (2) (2): 10b + a - 10a - b = 45 -9a + 9b = 45 -a + b = 5 ...... (3) (1)+(3): 2b = 14 b = 7 Put b = 7 into (1): a + (7) = 9 a = 2 Ans: The original number is 27. =
其他解答:
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