8條數!20點－百科全書

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8條數!20點

發問:

如果a=1,b=2,c=3,d=0(要式同答案) 1.2a+3b-c 2.c-2a+b 3.c(4a-2b) 4.a+b分之c-3d 更新: 5.c=30 F=5分之9 C+32 F=? 6.n=5 I=180(n-2) I=? 7.a=15 r=6 S=r-1分之a S=? 8.n=100 S=2分之1 n(n+1) S=?

最佳解答:

1. 2a+3b-c = (2x1) + (3x2) - 3 = 2 + 6 - 3 = 8 - 3 = 5 2. c-2a+b = 3 - (2x1) +2 = 3 - 2 + 2 = 1 + 2 = 3 3. c(4a-2b) = 3 x [(4x1) - (2x2)] = 3 x [4 - 4] = 3 x 0 = 0 4. a+b分之c-3d = 3 - (3x0) 1+2 = 3-0 3 = 3 除 3 = 1 5. c=30 F=5分之9 C+32 (9x30)+32 5 = (270+32) 除 5 = 302除 5 = 60.....2 6.n=5 I=180(n-2) = 180 x (5-2) = 180 x 3 = 540 I = 540 7. a=15 r=6 S=r-1分之a = 15 除 (6-1) = 15除5 = 3 S = 3 8.n=100 S=2分之1 n(n+1) = [1x100 x (100+1)] 除 2 = [100 x 101] 除 2 = 10,100 除 2 = 5,050 S=5,020 2009-07-29 12:08:07 補充：第8題打錯數字呀 : 8.n=100 S=2分之1 n(n+1) = [1x100 x (100+1)] 除 2 = [100 x 101] 除 2 = 10,100 除 2 = 5,050 S=5,050 **樓下的第 4 和第 5 題是否抄錯題目呢?

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