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f.4 math help~~
發問:
Q.1 3x^(-1/3)-1=8 Q.2 2(1/3x - 1)^ -3=54
最佳解答:
(1) 3x^(-1/3)-1=8 Let y=x^(-1/3) 3y-1=8 3y=9 y=3 x^(-1/3)=3 1/x^(1/3)=3 x^(1/3)=1/3 x=1/3^(1/3) (2) 2(1/3x-1)^(-3)=54 If you mean: Situation 1: 2[1/(3x-1)]^(-3)=54 [1/(3x-1)]^(-3)=27 1/(3x-1)=27^(-1/3) 3x-1=3 3x=4 x=4/3 Situation 2: 2(1/3x -1)^(-3)=54 (1/3x -1)^(-3)=27 1/3x -1=1/3 1/3x=4/3 3x=3/4 x=1/4
其他解答:
Q.1 3x^(-1/3)-1=8 3x^(-1/3)-1=8 3x^(-1/3) = 9 x^(-1/3) = 3 (x^-1/3)^3 = 3^3 x^-1 = 27 x = 1/27 Q.2 2(1/3x - 1)^-3=54 2(1/3x - 1)^-3=54 (1/3x - 1)^-3=27 (1/3x - 1)^3=1/3^3 1/3 x – 1 = 1/3 (全式乘 3) x – 3 = 1 x = 4
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