SAT II Math I : SAT Subject Test in Math I

Study concepts, example questions & explanations for SAT II Math I

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Example Questions

Example Question #4 : Ratios And Proportions

If for every  inch on a map it represents  miles, how many inches will be needed for a distance of  miles?

Possible Answers:

Correct answer:

Explanation:

The ratio of inches to miles is 

 

so you can set up a proportion of .  

You then cross multiply to get 

.  

Then you solve for the variable by dividing by  which gives us 

.

Example Question #37 : Mathematical Relationships

In a geometric sequence the ratio of the first term to the third term is 9:1. What is the ratio of the second term to the fifth term?

Possible Answers:

Correct answer:

Explanation:

Recall that in a geometric sequence there is a constant ratio between any pair of consecutive terms:

If the ratio of the first term to the third term is 9:1 then the ratio of two consecutive terms is a number that when multiplied by itself is 9:

Therefore the common ratio for this sequence is 3.

There are three terms between term 2 and 5 so the common ratio will be applied to the second term three times to get the fifth term: 

Since  for this sequence

 

Example Question #1 : Matrices

Define .

Give .

Possible Answers:

 is not defined.

Correct answer:

 is not defined.

Explanation:

The inverse of a 2 x 2 matrix  , if it exists, is the matrix 

First, we need to establish that the inverse is defined, which it is if and only if determinant .

Set , and check:

The determinant is equal to 0, so  does not have an inverse.

Example Question #2 : Matrices

Give the determinant of the matrix 

Possible Answers:

Correct answer:

Explanation:

The determinant of the matrix  is 

Substitute :

Example Question #1 : How To Add Matrices

Simplify:

Possible Answers:

Correct answer:

Explanation:

Matrix addition is very easy! All that you need to do is add each correlative member to each other. Think of it like this:

Now, just simplify:

There is your answer!

Example Question #2 : Matrices

Simplify:

Possible Answers:

Correct answer:

Explanation:

Matrix addition is really easy—don't overthink it! All you need to do is combine the two matrices in a one-to-one manner for each index:

Then, just simplify all of those simple additions and subtractions:

Example Question #1 : Matrices

Evaluate: 

Possible Answers:

Correct answer:

Explanation:

This problem involves a scalar multiplication with a matrix. Simply distribute the negative three and multiply this value with every number in the 2 by 3 matrix. The rows and columns will not change.

Example Question #1 : Matrices

Simplify:

Possible Answers:

Correct answer:

Explanation:

Scalar multiplication and addition of matrices are both very easy. Just like regular scalar values, you do multiplication first:

The addition of matrices is very easy. You merely need to add them directly together, correlating the spaces directly.

Example Question #1 : Multiplication Of Matrices

What is ?

Possible Answers:

Correct answer:

Explanation:

You can begin by treating this equation just like it was:

That is, you can divide both sides by :

Now, for scalar multiplication of matrices, you merely need to multiply the scalar by each component:

Then, simplify:

Therefore, 

Example Question #1 : Find The Sum Or Difference Of Two Matrices

Given the following matrices, what is the product of  and ?

 

Possible Answers:

Correct answer:

Explanation:

When subtracting matrices, you want to subtract each corresponding cell.

 

 

Now solve for  and 

 

 

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