Solving exponential and logarithmic equations worksheet with answers pdf

Solving exponential and logarithmic equations worksheet with answers pdf

Solving Exponential & Logarithmic Equations

Properties of Exponential and Logarithmic Equations

Let be a positive real number such that , and let and be real numbers. Then the following properties are

true:

1.



2.





Inverse Properties of Exponents and Logarithms

Base a Natural Base e

1.



2.





Solving Exponential and Logarithmic Equations

1.To solve an exponential equation, first isolate the exponential expression, then take the logarithm of both sides

of the equation and solve for the variable.

2.To solve a logarithmic equation, first isolate the logarithmic expression, then exponentiate both sides of the

equation and solve for the variable.

For Instance: If you wish to solve the equation, , you exponentiate both sides of the equation to solve it

as follows:

 Original equation



Exponentiate both sides

Inverse property

Or you can simply rewrite the logarithmic equation in exponential form to solve (i.e. 

).

Note: You should always check your solution in the original equation.

Example 1:

Solve each equation.

a.!

"

#! b.$%

Solution:

a.!

"

#! Original Equation

!

"

!

&

Rewrite with like bases

'% Property of exponential equations

Subtract 2 from both sides

The solution is 1. Check this in the original equation.

b.$% Original Equation

$% Property of logarithmic equations

 ! Add 3 to both sides

( Divide both sides by 2

The solution is 7. Check this in the original equation.

Example 2:

Solve )'

"*

.

Solution:

) '

"*

 Original Equation

"*

) Subtract 5 from both sides



"*

) Take the logarithm of both sides

' ) Inverse Property

$')+,(- Subtract 1 from both sides

Check:

)'

"*

 Original Equation

)'

*,./0"*

 Substitute 1.708 for

)'

,./0

 Simplify

)'!,111+ Solution checks