Finding the station of a log function is as simple as adhering to the said steps below. You will realize later after see some examples that many of the work-related boils down to resolving an equation. The key steps associated include isolating the log in expression and also then rewriting the log equation into an exponential equation. Girlfriend will watch what I average when you go over the worked instances below.

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Steps to uncover the train station of a Logarithm

STEP 1: replace the duty notation f\left( x \right) through y.

f\left( x \right) \to y

STEP 2: move the functions of x and y.

x \to y

y \to x

STEP 3: isolate the log expression on one side (left or right) of the equation.


STEP 4: transform or change the log in equation into its tantamount exponential equation.

Notice the the subscript b in the \log kind becomes the base through exponent N in exponential form.The variable M remains in the exact same place.

STEP 5: settle the exponential equation for y to obtain the inverse. Then change y by f^ - 1\left( x \right) which is the train station notation to compose the last answer.

Rewrite \colorbluey together \colorredf^ - 1\left( x \right)

Examples of how to discover the station of a Logarithm

Example 1: discover the inverse of the log equation below.

f\left( x \right) = \log _2\left( x + 3 \right)

Start by replacing the function notation f\left( x \right) by y. Then, interchange the roles of \colorredx and \colorredy.


Proceed by fixing for y and replacing the by f^ - 1\left( x \right) to gain the inverse. Component of the solution listed below includes rewriting the log equation into an exponential equation. Here’s the formula again that is provided in the conversion process.

Notice how the base 2 the the log expression i do not care the base through an exponent the x. The stuff inside the parenthesis stays in its original location.

Once the log in expression is unable to do by convert it right into an exponential expression, we can finish this off by individually both sides by 3. Don’t forget to replace the change y through the inverse notation f^ - 1\left( x \right) the end.


One way to check if we got the exactly inverse is come graph both the log equation and also inverse duty in a single xy-axis. If their graphs room symmetrical follow me the heat \large\colorgreeny = x, climate we deserve to be confident that our price is indeed correct.

Example 2: find the station of the log function

f\left( x \right) = \log _5\left( 2x - 1 \right) - 7

Let’s add up some level of an obstacle to this problem. The equation has actually a log expression being subtracted by 7. I hope you have the right to assess that this trouble is exceptionally doable. The solution will be a little messy yet definitely manageable.

So I begin by an altering the f\left( x \right) right into y, and also swapping the functions of \colorredx and \colorredy.

Now, we have the right to solve for y. Add both sides of the equation through 7 to isolation the logarithmic expression on the ideal side.

By effectively isolating the log expression on the right, us are all set to convert this right into an exponential equation. Observe the the basic of log in expression i m sorry is 6 i do not care the basic of the exponential expression top top the left side. The expression 2y-1 inside the parenthesis top top the ideal is now by itself without the log operation.

After doing so, proceed by addressing for \colorredy to achieve the compelled inverse function. Perform that by adding both sides by 1, adhered to by dividing both sides by the coefficient that \colorredy which is 2.

Let’s map out the graphs of the log and also inverse features in the same Cartesian aircraft to verify that they are indeed symmetrical along the line \large\colorgreeny=x.

Example 3: discover the inverse of the log function

So this is a little an ext interesting 보다 the very first two problems. Observe that the base of log in expression is missing. If you conference something prefer this, the presumption is that we are working through a logarithmic expression with base 10. Constantly remember this concept to aid you get roughly problems through the exact same setup.

I expect you are already much more comfortable with the procedures. We begin again by do f\left( x \right) together y, climate switching around the variables \colorredx and also \colorredy in the equation.

Our next goal is to isolation the log expression. We have the right to do that by individually both sides by 1 complied with by separating both sides by -3.

The log expression is now by itself. Remember, the “missing” base in the log expression implies a base of 10. Change this right into an exponential equation, and also start solving for y.

Notice the the entire expression top top the left side of the equation i do not care the exponent that 10 i m sorry is the implied basic as mentioned before.

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Continue addressing for y by subtracting both political parties by 1 and also dividing by -4. After y is fully isolated, replace that by the inverse notation \large\colorbluef^ - 1\left( x \right). Done!

Graphing the original role and its station on the very same xy-axis reveals that they room symmetrical about the heat \large\colorgreeny=x.

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