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5.兩個數的差是26，如果從大數的3/4減去小數的兩倍，所得的差是2。求大數。 6.XX的年齡是YY的兩倍。3年後，他們的歲數的和是42歲。XX現年幾歲? 7.從a的兩倍減去a的1/3，結果是10。求a的值。 8.XX的年齡比YY多5歲。4年後，他們的歲數的和是33歲。XX現年幾歲? 9.已知較小的數的3倍比較大的數的2倍多6。而兩數的和是17。求該兩數。 請例式+步驟...................thx
最佳解答:
最好用聯立去做，易明，無咁煩 5)設大數為x小數為y x-y=26....(1) x-2y=2.....(2) x=26+y....(3) 把3代入2 (26+y)-2y=2 y=24 把y=24代入(1) x-(24)=26 x=50 大數為50 6)x=2y.....(1) (3+x)+(3+y)=42.....(2) 把(1)代入(2) 3+(2y)+3+y=42 y=6 把y=6代入(1) x=2(6) x=12 7) 2a-1/3a=10 a=6 8)x-y=5....(1) (4+x)+(4+y)=33....(2) x=5+y....(3) 把(3)代入(2) 4+(5+y)+4+y=33 y=6 把y=6代入(1) x-(6)=5 x=11 X現年11歲 9)設較小數為x，較大數為y 3x=2y+6....(1) x+y=17....(2) 從(2)... x=17-y....(3) 把(3)代入(1)] 3(17-y)=2y+16 5y=45 y=9 把y=9代入(2) x+(9)=17 y =8 希望以上計ge數無錯 2006-12-31 13:56:16 補充： 第9條最後係x=8唔係y=8(手快打錯)
其他解答:
Q.5 = 40 Q.6 = 24 Q.7 = 6 Q.8 = 10 Q.9 = 9|||||Q5 設大數是X,小數是Y X - Y = 26 X - 26 = Y 3/4X - 2Y = 2 代入 3/4X - 2( X - 26 ) = 2 3/4X - 2X + 52 = 2 - 5/4X = - 50 X = 40 Q6 X = 2Y X/2 = Y X + 3 + Y + 3 = 42 X + Y +6 = 42 X + Y = 36 代入 X + X/2 = 36 1.5X = 36 X = 24 Q7 2a - 1/3a = 10 5/3a = 10 a = 6 Q8 X + 5 = Y X + 4 + Y + 4 = 33 X + Y + 8 = 33 X + Y = 25 代入 X + X + 5 = 25 2X + 5 = 25 2X = 20 X = 10 Q9 設大數是X,小數是Y 3Y - 2X = 6 X + Y = 17 X = 17 - Y 3Y - 2( 17 - Y ) = 6 3Y - 34 + 2Y = 6 5Y - 34 = 6 5Y = 40 Y = 8 X + 8 = 17 X = 9|||||5.設大數為x, 小數為y, x - y = 26 .....(1) 3x/4 - 2y = 2 .....(2) From (1), x - y = 26 y = x - 26 ...(3) sub (3) into (2) 3x/4 - 2(x - 26) = 2 3x - 8(x - 26) = 8 3x - 8x + 208 = 8 -5x = -200 x = 40 大數為40 6. 設XX的歲數為a, YY的歲數為b, a = 2b...(1) a + 3 + b +3 = 42...(2) sub (1) into (2), 2b + 3 + b +3 = 42 3b = 36 b = 12...(3) sub (3) into (1), a = 24 XX現年24歲 7. 2a - a/3 = 10 6a - a = 30 5a = 30 a = 6 8. 設XX的歲數為a, YY的歲數為b, a - b = 5...(1) a + 4 + b + 4 = 33...(2) Form (1) b = a - 5...(3) Sub (3) into (2) a + 4 + a - 5 + 4 = 33 2a = 30 a = 15 XX現年15歲 9. 設較大的數為x, 較小的數為y, 3y - 2x = 6...(1) x + y = 17...(2) From (2), x + y = 17 x = 17 - y...(3) Sub (3) into (1) 3y - 2(17 - y) = 6 3y - 34 + 2y = 6 5y = 40 y = 8...(4) Sub (4) into (3), x = 17 - 8 x = 9 較大的數為9 較小的數為8 2006-12-31 13:49:43 補充： 上面o個個...第9條y = 9 之後...你sub 左...跟住y 又 = 8?
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