標題:
呢條數唔係好明點計...
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發問:
佢個問題係咁既:::: The sum of the digits of a two-digit number is 8. If the digits are reversed, the value of the number is decreased by 54. What is the original number. 我淨係明佢話個數係兩位數,, 之後個兩個數字加埋會係=8.. 但係跟住個句我就唔係好明,, 可唔可以話我知點解同埋有埋條算式??
最佳解答:
Define the number as xy Not x times y, but x, y are the tens and units digit Example: if the number is 12, then x=1, y=2 Then the original number is 10x+y The new number is 10y+x (you can get this conclusion easily) So (10x+y) - (10y+x)=54 (because If the digits are reversed, the value of the number is decreased by 54.) Solving, we get x-y=6 ...(1) From the question, x+y=8...(2) Adding (1) and (2) 2x=14 x=7 So by x+y=8, y=1 So therefore the original number is 71 You can easily check that this is the answer Hope this can help you Note: reversing the digits mean: If 12 is reversed, then it becomes 21 If 83 is reversed, it becomes 38 If 123 is reversed, it becomes 321
其他解答:
條問題係解: 有一個兩位數 兩個單位加埋係8 如果呢個數調轉呢兩個位 數值就會低左54 問原數係幾多 for example the original number is 42 the two digit are 4 and 2 sum of them are 6 if i reversed it, it will become 24 the value of the number is decreased by 18 另外我俾埋呢條問題ge solution 你 let the ten digit number be x the digit number be y x+y=8----------------(1) 10x+y-(10y+x)=54 10x+y-10y-x=54 9x-9y=54 x-y=6-----------------(2) (1)+(2) 2x=14 x=7 y=1 i.e the original number is 71|||||如果2 個數字掉轉個位,, 俾原本果個少54 ,, 問你原本果個係咩 let x and y be the 2 number of 2 digits x=8-y.....(1) (10x+y)-54=10y+x ....(2)
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