Questions about Maths

1. Let x be the smaller and ( x+1 ) be the larger respectively .
x + ( x + 1 ) = 85
2x + 1 = 85
x = 42
The lager = x + 1
= 42 + 1
= 43
so the two consecutive numbers are 42 and 43.

( 1 ) The smaller = 24 - 1 = 23
( 2 ) The sum = N + ( N-1 ) = 2N -1

2.Let x be the smaller and ( x+2 ) be the larger respectively .
x + ( x + 2 ) = 118
2x + 2 = 118
x = 58
The lager = x + 2
= 58 + 2
= 60
so the two consecutive even integers are 58 and 60.

( 1 ) The smaller = 34 - 2 = 32
( 2 ) The smaller = N - 2

3. Let x be the value of the middle one.
( x - 1 ) + x + ( x + 1 ) = 117
3x = 117
x = 39
so the middle one is 39.

( 1 ) The smallest one = 13 - 1 = 12
The largest one = 13 + 1 = 14
( 2 ) The smallest one = N - 1
The largest one = N + 1

4.Let x be the smallest one .
x + ( x + 1) + ( x + 2 ) = 54
3x + 3 = 54
x = 17
The middle one = 17 + 1 =18
The largest one = 17 + 2 = 19
so the three consecutive numbers are 17 , 18 and 19 respectively .

5. Let x be the smallest one.
x + ( x +1 ) + ( x +2 ) + ( x + 3) = 42
4x + 6 = 42
x = 9
so the four consecutive integers are 9 , 10 , 11 , 12 .

2008-08-02 18:26:37 補充：
consecutive number : 即連續數
所以要計 consecutive number , 只是加 1 或者 減 1 , 視乎你定大的數為未知數或者家較小的數 , 不難計算的 , 只要分清楚你定那個數為未知數。
別以為所有連續數都是加 1 , 要看清楚有沒有 even 或者 odd 的字眼 , 前者解雙數 , 後者解單數 , 這個情況就是加 2 , 而不是加 1 , 因為每個連續數之間相差了 2 。
希望幫到你以後面對這類題目啦 ~~~ ^^