please teach me how to do this 4^x+6(4)^-x=5
the answers is x=In756=6.628.
I need steps.
更新1:
sorry, the answer is x=In2/In4=0.5 or In3/In4=0.792
Solve the equation?
2008-01-24 6:10 pm
Solve the equation?
please teach me how to do this 4^x+6(4)^-x=5
the answers is x=In756=6.628.
I need steps.
please teach me how to do this 4^x+6(4)^-x=5
the answers is x=In756=6.628.
I need steps.
回答 (3)
2008-01-24 8:14 pm
✔ 最佳答案
Q: Please teach me how to do this 4x ＋ 6* 4-x ＝ 5 Sol:
Let A ＝ 4x
4x ＋ 6* 4-x ＝ 5
A ＋ 6/A ＝ 5
A2 － 5A ＋ 6 ＝ 0
( A － 2 ) ( A － 3 ) ＝ 0
A ＝ 2 or A ＝ 3
4x ＝ 2 or 4x ＝ 3
㏑4x ＝ ㏑2 or ㏑4x ＝ ㏑3
x㏑4 ＝ ㏑2 or x㏑4 ＝ ㏑3
x ＝ ㏑2/㏑4 or x ＝ ㏑3/㏑4
x ＝ 0.5 or x ≒ 0.79 ( to 2 d.p )
Ans: x ＝ 0.5 or x ≒ 0.79
Send me a letter if any steps you don’t understand.
參考: 數學小頭腦
2008-01-28 5:31 am
Excellent !!!
2008-01-24 6:57 pm
4^x+6 [x^(-4)]=5
let y = 4^x
y+6/y=5
y^2-5y+6=0
(y-6)(y+1)=0
y=6 or y=-1
since y=4^x >0 , so we reject y=-1
4^x=6
ln (4^x)=ln6
x ln 4= ln6
x=ln6/ln4=1.29
your answer is not correct.
let y = 4^x
y+6/y=5
y^2-5y+6=0
(y-6)(y+1)=0
y=6 or y=-1
since y=4^x >0 , so we reject y=-1
4^x=6
ln (4^x)=ln6
x ln 4= ln6
x=ln6/ln4=1.29
your answer is not correct.
收錄日期: 2021-04-23 22:36:57
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