(2^x)- -(2^x-1)=4
(3^x+2) - (3^x) = 72
2(3^x+1) - 5(3^x) = 9
f.3 math..指數定律
2007-09-25 8:22 pm
回答 (1)
2007-09-25 8:30 pm
✔ 最佳答案
1)2^x - 2^(x-1) = 4
2^x (1 - 2^-1) = 4
2^x (1/2) = 4
2^x = 8
2^x = 2^3
x = 3
2)
3^(x+2) - 3^x = 72
3^x (3^2 - 1) = 72
3^x (9-1) = 72
3^x (8) = 72
3^x = 9
3^x = 3^2
x = 2
3)
2*3^(x+1) - 5(3^x) = 9
3^x(2*3 - 5) = 9
3^x (6-5) = 9
3^x = 9
3^x = 3^2
x = 2
參考: I am a maths tutor
收錄日期: 2021-04-13 19:02:55
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