All ACT Math Resources
Example Questions
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.
Example Question #801 : Algebra
If , then ?
10
4
5
25
15
5
Calculate the power of that makes the expression equal to 25. We can set up an alternate or equivalent equation to solve this problem:
Solve this equation by taking the square root of both sides.
, because logarithmic equations cannot have a negative base.
The solution to this expression is:
Example Question #802 : Algebra
If and , then which of the following CANNOT be the value of ?
Even roots of numbers can either be positive or negative. Thus, x = +/- 5 and y = +/- 3. The possible values from x + y can therefore be:
(-5) + (-3) = -8
(-5) + 3 = -2
5 + (-3) = 2
5 + 3 = 8