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標題:
A+B+C=......D=?
發問:
我想問問: A+B+C=14 A+B+D=17 A+C+D=20 B+C+D=21 D=?
最佳解答:
A+B+C=14……..(i) A+B+D=17……..(ii) A+C+D=20……..(iii) B+C+D=21……..(iv) (i) + (ii) + (iii) + (iv), we get (A+B+C) + (A+B+D) + (A+C+D) + (B+C+D) = 14 + 17 + 20 + 21 thus, 3A + 3B + 3C + 3D = 75 3D = 72 - 3A - 3B - 3C 3D = 72 - 3(A + B + C) 3D = 72 - 3(14)........................(given A+B+C=14) 3D = 72 - 42 3D = 30 D = 10
3 + 4 + 7 = 14 3 + 4 + 10 = 17 3 + 7 + 10 = 20 4 + 7 + 10 = 21 A = 3 B = 4 C = 7 D = 10|||||d=10 c=7 b=4 a=3|||||10 因為b>a=1 c>b=3 d>c=3 所以d=10,then c=7,then b=4 10+7+4=21 b+c+d=21
A+B+C=......D=?
發問:
我想問問: A+B+C=14 A+B+D=17 A+C+D=20 B+C+D=21 D=?
最佳解答:
A+B+C=14……..(i) A+B+D=17……..(ii) A+C+D=20……..(iii) B+C+D=21……..(iv) (i) + (ii) + (iii) + (iv), we get (A+B+C) + (A+B+D) + (A+C+D) + (B+C+D) = 14 + 17 + 20 + 21 thus, 3A + 3B + 3C + 3D = 75 3D = 72 - 3A - 3B - 3C 3D = 72 - 3(A + B + C) 3D = 72 - 3(14)........................(given A+B+C=14) 3D = 72 - 42 3D = 30 D = 10
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其他解答:3 + 4 + 7 = 14 3 + 4 + 10 = 17 3 + 7 + 10 = 20 4 + 7 + 10 = 21 A = 3 B = 4 C = 7 D = 10|||||d=10 c=7 b=4 a=3|||||10 因為b>a=1 c>b=3 d>c=3 所以d=10,then c=7,then b=4 10+7+4=21 b+c+d=21
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