数学...指数解方程 F.4
发布网友
发布时间：2024-10-17 22:38
共1个回答
热心网友
时间：2024-11-14 12:09
更新1:
第1题答案系 4 第2题答案系 -7
1. 2[1/(3x-1)]^(-3) =54 [1/(3x-1)]^(-3) = 27 (3x – 1)^3 = 3^3 3x – 1 = 3 3x = 4 x = 4/3 2. [2/(5x+3)]^(-2) =25 [(5x + 3)/2]^2 = 25 (5x + 3)^2 = 100 (5x + 3)^2 – 10^2 = 0 (5x + 3 + 10)(5x + 3 – 10) = 0 (5x + 13)(5x – 7) = 0 x = -2.6 or x = 1.4 2010-01-23 12:16:22 补充： (1) 2[(1/3)x –1]^(-3) = 54 [(1/3)x –1]^(-3) = 27 = 3^3 (1/3)x –1 = 1/3 (1/3)x = 4/3 x = 4 (2) [(2/5)x + 3]^(-2) = 25 = 5^2 [(2/5)x + 3]^2 = 1/5^2 (2/5)x + 3 = +/- 1/5 (2/5)x = -16/5 or -14/5 x = - 7 or -8 (not only -7)
