1) the sum of a number and 13 equals 3 times the result of the number minus 11.Find the number.
2) In 3 consecutive numbers,the smallest number is 19/20 of the largest one,find the middle number.
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f.1 MATH![急.]
2008-05-30 12:15 am
回答 (2)
2008-06-08 12:45 am
✔ 最佳答案
1. Let x be the number(x 13) = 3 (x-11)
x 13 = 3x - 33
x - 3x = -13 - 33
-2x = - 46
x = 23
2. Let x be the middle number
19
(x -1) = ( x 1 ) 一
20
x - 1 = ( x 1 ) 0.95
x - 1 = 0.95x 0.95
x - 0.95x = 1 0.95
0.05x = 1.95
x = 39
So, the middle number is 39 .
2008-06-07 16:46:03 補充：
第二題係
2. Let x be the middle number
19
(x -1) = ( x +1 ) 一
20
x - 1 = ( x +1 ) 0.95
x - 1 = 0.95x + 0.95
x - 0.95x = 1 + 0.95
0.05x = 1.95
x = 39
So, the middle number is 39 .
2008-05-30 12:20 am
1. number+13=3(number-11)
2no. =13+33
no=23
2. let the middle no. be y
(y-1)=19(y+1)/20
y/20=39/20
y=39
the middle no is 39
2no. =13+33
no=23
2. let the middle no. be y
(y-1)=19(y+1)/20
y/20=39/20
y=39
the middle no is 39
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