標題:
數學F.1
發問:
The sum of three consecutive even numbers is 42.Find the three numbers. The sum of three consecutive odd numbers is 81.Find the three numbers. 要步驟，THX~
最佳解答:
1. Let the smallest even number be 2m then the other two are 2m + 2 and 2m + 4 respectively 2m + (2m + 2) + (2m + 4) = 42 6m + 6 = 42 6m = 36 m = 6 So, the smallest number is 2 X 6 = 12 And the other two are (12 + 2) and (12 + 4) = 14 and 16 2. Let the smallest even number be 2m + 1 then the other two are 2m + 3 and 2m + 5 respectively (2m + 1) + (2m + 3) + (2m + 5) = 81 6m + 9 = 81 6m = 72 m = 12 So, the smallest number is 2 X 12 + 1 = 25 And the other two are (25 + 2) and (25 + 4) = 27 and 29
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其他解答:
1) Let y ,(y+2),(y+4) be the 1st,2nd and 3rd no respectively. y+(y+2)+(y+4)=42 3y+6=42 3y=36 y=12 Since,y=12,y+2=14 and y+4=16 Therefore,the 1st no is 12, 2nd no is 14 and the 3rd no is 16 2) Let a,(a+2),(a+4) be the 1st,2nd,and the 3rd no respectively a+(a+2)+(a+4)=81 3a+6=81 3a=75 a=25 Since,a=25,a+2=27 and a+4=29 Therfore,the 1st no is 25,the 2nd no is 27 and the 3rd no is 29 Hope these answers can help you~ If you have any questions in the future,you can ask me~|||||let x be the smallest number x+(x+2)+(x+4)=42 3x+6=42 3x=36 x=12 The three numbers are 12,14,16 let x be the smallest number x+(x+2)+(x+4)=81 3x+6=81 3x=75 x=25 The three numbers are 25,27,29|||||a) let x係第一個even no, 另外兩個even number就係x+2同x+4 x+(x+2)+(x+4)=42 3x+6=42 3x=36 x=12 所以3個no,係12,14,16 b) let y係第一個even no, 另外兩個even number就係y+2同y+4 y+(y+2)+(y+4)=81 3y+6=81 3y=75 y=25 所以3個no.係25,27,29
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