All ACT Math Resources
Example Questions
Example Question #101 : Exponents
What is the value of ? Round to the nearest hundredth.
You could solve this by using your calculator. Remember that you will have to translate this into:
Another way you can solve it is by noticing that
This means you can rewrite your logarithm:
Applying logarithm rules, you can factor out the power:
For any value , . Therefore, . So, your answer is .
Example Question #2291 : Act Math
Solve for
.
Round to the nearest hundredth.
To solve an exponential equation like this, you need to use logarithms. This can be translated into:
Now, remember that your calculator needs to have this translated. The logarithm is equal to the following:
, which equals approximately .
Remember that you have the equation:
Thus, .
Example Question #2292 : Act Math
Solve the following equation
.
In order to solve a question like this, you will need to use logarithms. First, start by converting this into a basic logarithm:
Recall that you need to convert for your calculator:
, which equals approximately
Thus, you can solve for :
Example Question #2293 : Act Math
At the end of each year, an account compounds interest at a rate of . If the account began with , how many years will it take for it to reach a value of , presuming no withdrawals or deposits occur?
The general function that defines this compounding interest is:
, where is the number of years.
What we are looking for is:
You can solve this using a logarithm. First, isolate the variable term by dividing both sides:
Which is:
Next, recall that this is the logarithm:
For this, you will need to do a base conversion:
This is
This means that it will take years. is too few and at the end of , you will have over .
Example Question #2294 : Act Math
What is the value of ? Round to the nearest hundredth.
Remember that you will need to calculate your logarithm by doing a base conversion. This is done by changing into:
Using your calculator, you can find this to be:
or approximately
Example Question #11 : How To Find A Logarithm
if , what is ?
The first step of this problem is to find
by expanding to the formula
y is found to be 2. The next step is to plug y in to the second log.
, which expands to
Example Question #101 : Exponents
Find .
expands to
expands to
Example Question #11 : Logarithms
Simplify:
Here, we need to make use of some logarithm identities:
Therefore, putting all of those things together, we get the final answer of
Example Question #11 : Logarithms
If
,
then what is ?
This is a test of translating logarithmic/exponential properties, with the key here being to realize that
is equivalent to .
With that in mind, here is how it works out:
Hence, .
Example Question #12 : Logarithms
can be written as which of the following?
A.
B.
C.
B and C only
A only
B only
A, B and C
A and B only
A, B and C
A is true in two ways. You can use the fact that if a logarithm has no base, you can use base 10, or you can use the fact that you can use this property:
B is a simple change of base application, and C is simply computing the logarithm.