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Math Question

發問:

The sum of a two-digit number is 8. If the digits are reserved, the new number is greater than the product of the digit by 38. Find the original number. 更新: The sum of digits of a two-digit number is 8.

最佳解答:

• 懷孕36周可否吃首烏芝麻糊-
• (急)英文作文-動物應否住動物園(40點)
• maths questions (area of circle)-

• 懷孕36周可否吃首烏芝麻糊-
• (急)英文作文-動物應否住動物園(40點)
• maths questions (area of circle)-

 

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Let the two-digit number be 10A + B The sum of digits of a two-digit number is 8 : A + B = 8...(1) If the digits are reserved, the new number is greater than the product of the digit by 38 : 10B + A = AB + 38...(2) By (1) : A = 8 - B , sub it to (2) : 10B + (8 - B) = B(8 - B) + 38 9B + 8 = 8B - B^2 + 38 B^2 + B - 30 = 0 (B - 5)(B + 6) = 0 B = 5 or B = - 6 (rejected) A = 8 - 5 = 3 The original number is 35

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