If you would like an in-depth review of exponents, the rules of exponents, exponential functions and exponential equations, click on exponential function.
Solve for x in the following equation.
Exact answer: Approximate answer:
The first step is to isolate
Add 4 to both sides of the equation.
Divide both sides of the equation by 50.
Take the natural logarithm of both sides of the equation
The exact answer is and the approximate answer is
When solving the above problem, you could have used any logarithm. For example, let's solve it using the logarithm with base 30.
Check this answer in the original equation.
Check the solution by substituting -0.035093599722 in the original equation for x. If the left side of the equation equals the right side of the equation after the substitution, you have found the correct answer.
You can also check your answer by graphing (formed by subtracting the right side of the original equation from the left side). Look to see where the graph crosses the x-axis; that will be the real solution. Note that the graph crosses the x-axis at -0.035093599722. This means that -0.035093599722 is the real solution.
If you would like to review the solution to problem 7.6b, click on Problem
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