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1. 2[4^(x)]+4^(x+1)=24 Let x = a 2 × 4a + 4a?1 = 24 2 × 4a + 4 × 4a = 24 (2 + 4) × 4a = 24 4a = 4 a = 1?x = 1 2. 9^(x)-2[3^(2x-1)]=1 Let x = a 9a - 2 × 32a?1 = 1 32a - 2 × (32a / 3) = 1 (1 - ?) 32a = 1 32a = 3 2a = 1 a = ??x = ? 3. 3^(x + 2y) = 27 & 9^(2x + y) = 1 3^(x + 2y) = 33 x + 2y = 3..........? 9^(2x + y)=1 3^[2(2x + y)] = 3o 2(2x + y) = 0 2x + y = 0..........? ? → y = -2x into ?:x - 4x = 3 x = -1 y = 2 2011-05-26 04:46:48 補充: 因沒有上標符號 x,所以唯有 Let x = a,使顯示較為清楚。 實際運算時不需要這樣做。
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1. 2(4^(x))+4^(x+1)=24 2. 9^(x)-2(3^(2x-1))=1 3. 3^(x+2y)=27 & 9^(2x+y)=1最佳解答:
1. 2[4^(x)]+4^(x+1)=24 Let x = a 2 × 4a + 4a?1 = 24 2 × 4a + 4 × 4a = 24 (2 + 4) × 4a = 24 4a = 4 a = 1?x = 1 2. 9^(x)-2[3^(2x-1)]=1 Let x = a 9a - 2 × 32a?1 = 1 32a - 2 × (32a / 3) = 1 (1 - ?) 32a = 1 32a = 3 2a = 1 a = ??x = ? 3. 3^(x + 2y) = 27 & 9^(2x + y) = 1 3^(x + 2y) = 33 x + 2y = 3..........? 9^(2x + y)=1 3^[2(2x + y)] = 3o 2(2x + y) = 0 2x + y = 0..........? ? → y = -2x into ?:x - 4x = 3 x = -1 y = 2 2011-05-26 04:46:48 補充: 因沒有上標符號 x,所以唯有 Let x = a,使顯示較為清楚。 實際運算時不需要這樣做。
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