Question

2 ^ x = 3 ^ (x + 1) solve for x

Answer 1

Answer:

  -2.71

Step-by-step explanation:

This exponential equation can be solved by rewriting it so there is only one base, then using logarithms.

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solve for x

  2^x = 3^(x+1) . . . . . given

  2^x = 3·3^x . . . . . . eliminate the constant in the exponent

  (2/3)^x = 3 . . . . . . . divide by 3^x

  x·log(2/3) = log(3) . . . . take logarithms

  x = log(3)/log(2/3) ≈ -2.7095113

The value of x is about -2.71.

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Alternate solution

Taking logarithms transforms this exponential equation to a linear equation.

  x·log(2) = (x +1)·log(3) . . . . take logs

  x(log(2) -log(3)) = log(3) . . . . . . subtract x·log(3)

  x = log(3)/(log(2) -log(3)) = log(3)/log(2/3) . . . . . same result as above

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Additional comment

In the attached, we have used a graphing calculator to find the x-intercept of the function f(x) = 0, where f(x) = 2^x -3^(x+1). This is the solution to the given equation.

The applicable rules of logarithms are ...

  log(a^b) = b·log(a)

  log(a/b) = log(a) -log(b)