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Having trouble solving this equation:

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e^(6x)+6e^(3x)-27=0. fill in the blank Image provided?

asked Nov 4, 2014 in CALCULUS by anonymous

1 Answer

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The exponential equation e6x + 6e3x - 27 = 0

e(3*2*x) + 6e3x - 27 = 0

{Recall Power of a Power Property (am)n = amn}

(e3x)2 + 6e3x - 27 = 0

Let e3x = t

Now the equation becomes t2 + 6t - 27 = 0

Solve the above equation by using factorization.

t2 + 9t - 3t - 27 = 0

t(t + 9) - 3(t + 9) = 0

(t + 9)(t - 3) = 0

t + 9 = 0 and t - 3 = 0

t = - 9 and t = 3

Consider t = 3.

Back substitute t = e3x.

e3x = 3

Take ln on both side.

ln(e3x) = ln(3)

3x ln(e) = 1.09

3x (1) = 1.09

x = 1.09/3

Solution x = 0.363.

answered Nov 4, 2014 by david Expert
edited Nov 4, 2014 by david

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