Solve the logarithmic equation Be sure to reject any value t

Solve the logarithmic equation. Be sure to reject any value that is not in the domain of the original logarithmic expressions. Give the exact answer. log_3 (x + 3) - log_3 (x - 3) = 4

Solution

Given that

log3(x + 3) - log3(x - 3) = 4

log3(x + 3) - log3(x - 3) = log3(34) [ since , a = logb(ba) ]

log3(x + 3) - log3(x - 3) =  log3(81)

log3[ (x + 3)/(x - 3) ] =   log3(81) [ since , logc(a) - logc(b) = logc(a/b) ]

  (x + 3)/(x - 3) = 81 [ since ,if logbf(x) = logbg(x) then f(x) = g(x) ]

      (x + 3) = 81(x - 3)

x + 3 = 81x - 243

81x - x = 3 + 243

80x = 246

x = 246/80

x = 123/40

x = 3.075

  

 Solve the logarithmic equation. Be sure to reject any value that is not in the domain of the original logarithmic expressions. Give the exact answer. log_3 (x

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