1)解方程7(x-1)-5(2-x)=3
2)三個連續整數的和等於45,問這三個連續整數是多少?
數學題呀....
2007-07-28 9:31 pm
回答 (8)
2007-07-28 9:41 pm
7(x-1)-5(2-x) = 3
7x-7-10+5x = 3
12x = 20
x =5/3
2> 14,15,16
2007-07-28 13:43:37 補充：
x + ( x+1 ) + ( x+2 ) = 453x + 3 = 45 3x = 42 x = 14
7x-7-10+5x = 3
12x = 20
x =5/3
2> 14,15,16
2007-07-28 13:43:37 補充：
x + ( x+1 ) + ( x+2 ) = 453x + 3 = 45 3x = 42 x = 14
2007-07-28 9:40 pm
1) 7(x-1)-5(2-x)=3
7x-7-10-5x=3
2x-17=3
2x=3+17
x=20/2
x=10
2)以條要設第1or第2or第3個數係個未知數先
我就設中間個係n
第1個就係N-1
第2個就係n
第3個就係n+1
之後就將佢地加晒
(n-1)+n+(n+1)=45
n-1+n+n+1=45
3n=45
n=45/3
n=15
最後就求埋其如個2個數
第1個係n-1=14
第3個就係n+1=16
驗數:14+15+16=45
2007-07-28 13:42:36 補充：
1) 7(x-1)-5(2-x)=37x-7-10+5x=312x-17=312x=3+17x=20/12x=0.6 SORRY............打錯左
7x-7-10-5x=3
2x-17=3
2x=3+17
x=20/2
x=10
2)以條要設第1or第2or第3個數係個未知數先
我就設中間個係n
第1個就係N-1
第2個就係n
第3個就係n+1
之後就將佢地加晒
(n-1)+n+(n+1)=45
n-1+n+n+1=45
3n=45
n=45/3
n=15
最後就求埋其如個2個數
第1個係n-1=14
第3個就係n+1=16
驗數:14+15+16=45
2007-07-28 13:42:36 補充：
1) 7(x-1)-5(2-x)=37x-7-10+5x=312x-17=312x=3+17x=20/12x=0.6 SORRY............打錯左
參考: me^^
2007-07-28 9:40 pm
請問你讀緊幾年級?
1) 7(x-1)-5(2-x)=3
7x-7-10+5x=3
12x=20
x=1-2/3(1又2/3)
2) 14,15,16
1) 7(x-1)-5(2-x)=3
7x-7-10+5x=3
12x=20
x=1-2/3(1又2/3)
2) 14,15,16
2007-07-28 9:39 pm
1) 7(x-1)-5(2-x)=3
7x-7-10+5x=3
12x=20
x= 5/3 (or 1.6666....)
2) Let x be the number.
So, x+(x+1)+(x+2) = 45
3x+3=45
3x=42
x=14
I hope the answers are correct and useful.
7x-7-10+5x=3
12x=20
x= 5/3 (or 1.6666....)
2) Let x be the number.
So, x+(x+1)+(x+2) = 45
3x+3=45
3x=42
x=14
I hope the answers are correct and useful.
2007-07-28 9:39 pm
1)
7(X-1)-5(2-X)=3
7X-7-10+5X=3
12X-17=3
12X=20
X=20/12
X=5/3
2)
設Ｘ＝第一個數，Ｘ＋１＝第２個數，Ｘ＋２＝第３個數
Ｘ＋（Ｘ＋１）＋（Ｘ＋２）＝４５
３Ｘ＋３＝４５
３Ｘ＝４２
Ｘ＝１４
所以Ｘ＋１＝１５，Ｘ＋２＝１６
三個連續整數是１４，１５，１６
7(X-1)-5(2-X)=3
7X-7-10+5X=3
12X-17=3
12X=20
X=20/12
X=5/3
2)
設Ｘ＝第一個數，Ｘ＋１＝第２個數，Ｘ＋２＝第３個數
Ｘ＋（Ｘ＋１）＋（Ｘ＋２）＝４５
３Ｘ＋３＝４５
３Ｘ＝４２
Ｘ＝１４
所以Ｘ＋１＝１５，Ｘ＋２＝１６
三個連續整數是１４，１５，１６
2007-07-28 9:39 pm
2) let the first number to be x, we have x + (x + 1) + (x + 2) = 45
i.e. 3x + 3 = 45
3x = 42
x = 14
So, the numbers are 14, 15 and 16.
i.e. 3x + 3 = 45
3x = 42
x = 14
So, the numbers are 14, 15 and 16.
2007-07-28 9:38 pm
7(x-1)-5(2-x)=3
7x-7-10+5x=3
12x=20
x=5/3
設 x, x+1, x+2 為三個連續整數
x+(x+1)+(x+2)=45
3x=42
x=14
x+1=14+1=15
x+2=14+2=16
三個連續整數是14, 15, 16
7x-7-10+5x=3
12x=20
x=5/3
設 x, x+1, x+2 為三個連續整數
x+(x+1)+(x+2)=45
3x=42
x=14
x+1=14+1=15
x+2=14+2=16
三個連續整數是14, 15, 16
2007-07-28 9:35 pm
1)7(x-1)-5(2-x)=3
7x-7-10+5x=3
7x+5x=3+7+10
12x=20
x=0.6(如果冇錯就係0.6)
7x-7-10+5x=3
7x+5x=3+7+10
12x=20
x=0.6(如果冇錯就係0.6)
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