All SAT II Math II Resources
Example Questions
Example Question #2 : Matrices
If , what is ?
Begin by distributing the fraction through the matrix on the left side of the equation. This will simplify the contents, given that they are factors of :
Now, this means that your equation looks like:
This simply means:
and
or
Therefore,
Example Question #101 : Mathematical Relationships
Evaluate .
The element in row , column , of can be found by multiplying row of by row of - that is, by multiplying elements in corresponding positions and adding the products. Therefore,
Example Question #102 : Mathematical Relationships
The determinant of this matrix is equal to 4. Evaluate .
A matrix has as its determinant . Setting , this becomes
Set this determinant equal to 4 and solve for :
the correct response.
Example Question #103 : Mathematical Relationships
Let .
Which of the following real value(s) of makes a matrix without an inverse?
There are two such values: and
There is one such value:
There is one such value:
has an inverse for all real values of
There are two such values: and
There are two such values: and
A matrix lacks an inverse if and only if its determinant is equal to zero. The determinant of is
.
Setting this equal to 0:
Taking the square root of both sides:
The matrix therefore has no inverse if either or .
Example Question #104 : Mathematical Relationships
Let be the two-by-two identity matrix and .
Which matrix is equal to the inverse of ?
does not have an inverse.
; the two-by-two identity matrix is . Add the two by adding elements in corresponding positions:
.
The inverse of a two-by-two matrix is , where
.
We can find by setting . The determinant of is
Replacing:
;
simplifying the fractions, this is
Example Question #21 : Matrices
Let and .
Evaluate .
does not exist.
The inverse of any two-by-two matrix can be found according to this pattern:
If
then
,
where determinant is equal to .
Therefore, if , then , the first row/first column entry in the matrix , can be found by setting , then evaluating:
Example Question #105 : Mathematical Relationships
For which of the following real values of does have determinant of sixteen?
or
None of these
or
or
A matrix lacks an inverse if and only if its determinant is equal to zero. The determinant of is
We seek the value of that sets this quantity equal to 16. Setting it as such then solving for :
Therefore, either or .
Example Question #21 : Matrices
Let equal the following:
.
Which of the following values of makes a matrix without an inverse?
There are two such values: or
There is one such value:
There are two such values: or
There is one such value:
There is one such value:
There is one such value:
A matrix lacks an inverse if and only if its determinant is equal to zero. The determinant of is
Set this equal to 0 and solve for :
,
the only such value.
Example Question #1 : Sequences
Evaluate:
The series diverges
The series diverges
An infinite series converges to a sum if and only if . However, in the series , this is not the case, as . This series diverges.
Example Question #2 : Sequences
Give the next term in this sequence:
_______________
The key to finding the next term lies in the denominators of the third term onwards. They are terms of the Fibonacci sequence, which begin with the terms 1 and 1 and whose subsequent terms are each formed by adding the previous two.
The th term of the sequence is the number , where is the th number in the Fibonacci sequence (since the first two Fibonacci numbers are both 1, the first two terms being 0 fits this pattern). The Fibonacci number following 13 and 21 is their sum, 34, so the next number in the sequence is
.