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July 30, 2014

July 30, 2014

Posted by **MYA** on Wednesday, September 5, 2012 at 7:43pm.

(e^x-e^-x)/2=6

what is the exact answer?

x=?

what is the answer approx to 3 decimal places?

x=?

- college alg -
**Reiny**, Wednesday, September 5, 2012 at 8:17pm(e^x-e^-x)/2=6

e^x - e^-x = 12

multiply each term by e^x

(e^x)^2 - 1 = 12e^x

let y = e^x

y^2 -1 = 12y

y^2 - 12y - 1 = 0

(y-4)(y+3) = 0

y = 4 or y = -3

e^x = 4 or e^x = -3 , the latter part being impossible

so e^x = 4

take ln of both sides

ln e^x = ln4

x lne = ln4

x = ln4 or appr 1.386

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