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(PRE CALC)
What is the solution to the equation?

12ln(x+37)=ln(x2−25)−ln(x+5)

Responses

x = 1 and x = 12
x, = 1 and , x, = 12

x = 12 only
x, = 12 only

x=−12 only
x equals negative 12, only

x=−12 and x = 1

PRE CALC What is the solution to the equation 12lnx37lnx225lnx5 Responses x 1 and x 12 x 1 and x 12 x 12 only x 12 only x12 only x equals negative 12 only x12 a class=

Respuesta :

Answer:

  (a)  x = 12 only

Step-by-step explanation:

You want the solution to 1/2ln(x+37) = ln(x^2−25)−ln(x+5).

Graph

A graph of this written in the form ...

  [tex]\dfrac{1}{2}\ln{(x+37)}-(\ln{(x^2-25)}-\ln{(x+5)})=0[/tex]

shows one solution at x=12.

Antilog

The right side of the equation can be simplified to ...

  [tex]\dfrac{1}{2}\ln(x+37)=\ln{\left(\dfrac{x^2-25}{x+5}\right)}=\ln{(x-5)}\\\\x+37=(x-5)^2\qquad\text{multiply by 2; take antilogs}\\\\x^2-11x-12=0\qquad\text{subtract $x+37$}\\\\(x+1)(x-12)=0\qquad\text{factor}[/tex]

The argument of the ln function must be positive, so we require x > 5. The factors will be zero for x=-1 and x=12, but x=-1 is not in the domain of the original equation.

The only solution is x = 12.

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