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Can you solve this equation?
ln(2x-5)- ln(x)=1/4
show working
3 Answers
- Wayne DeguManLv 710 years agoFavorite Answer
ln[(2x - 5)/x] = 1/4
=> (2x - 5)/x = e^1/4
so, 2x - 5 = xe^1/4
=> 2x - xe^1/4 = 5
=> x(2 - e^1/4) = 5
i.e. x = 5/(2 - e^1/4) = 6.99 (3 s.f.)
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- 10 years ago
To answer this question, you must know the properties of ln. Remember:
ln(B)+ln(A)=ln(AB)
ln(B)-ln(A)=ln(B/A)
2ln(B)=ln(B^2)
e^ln(B)=B
With these rules, we can proceed.
so ln(2x-5)-ln(x)=1/4 becomes
ln((2x-5)/x)=1/4
Then, e^(ln(2x-5)/x)=e^(1/4)
So, (2x-5)/x=e^(1/4)
2x-5=xe^(1/4)
2x=xe^(1/4)+5
2x-xe^(1/4)=5
(Remember e^(1/4) is just a number. All you have to do from here is combine the like terms of x, and divide by the resulting coefficient)
- 10 years ago
ln(2x-5) - ln(x) = 1/4
or, ln((2x-5)/x) = 1/4
or, (2x-5)/x = e^(1/4)
or, 2x - 5 = xe^(1/4)
or, x = 5/(2-e^(1/4)) = 5/(2-1.284) from calculator
or, x = 6.983