請問以下x等於幾多
4-5^x+2=125 X 0.2^-x
數學(algebra)
2007-09-19 5:35 am
回答 (1)
2007-09-19 5:59 am
✔ 最佳答案
4 –5x+2 = 125( 0.2-x )4 – 5x ( 52 ) = 53 ( 1 / 5 )-x
4 – 5x ( 52 ) = 53 ( 5x )
4 = 5x ( 52 + 53 )
4 = 5x ( 150 )
5x = 2 / 75
log 5x = log ( 2 / 75 )
x log 5 = log ( 2 / 75 )
x = log ( 2 / 75 ) / log 5
x = -2.25 ( cor. to 3 s.f. )
參考: My Maths Knowledge
收錄日期: 2021-04-13 13:32:54
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