PSAT Math : Arithmetic

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #4 : How To Find The Square Of An Integer

How many integers from 20 to 80, inclusive, are NOT the square of another integer?

Possible Answers:

Correct answer:

Explanation:

First list all the integers between 20 and 80 that are squares of another integer:

52 = 25

62 = 36

72 = 49

82 = 64

In total, there are 61 integers from 20 to 80, inclusive. 61 – 4 = 57

Example Question #5 : How To Find The Square Of An Integer

Let the universal set  be the set of all positive integers.

Let  be the set of all multiples of 3; let  be the set of all multiples of 7; let  be the set of all perfect square integers. Which of the following statements is true of 243?

Note:  means "the complement of ", etc.

Possible Answers:

Correct answer:

Explanation:

, so 243 is divisible by 3. .

, so 243 is not divisible by 7.  - that is, .

, 243 is not a perfect square integer.  - that is, .

Since 243 is an element of , and , it is an element of their intersection. The correct choice is that

Example Question #5 : How To Find The Square Of An Integer

Consider the inequality:

Which of the following could be a value of ?

Possible Answers:

x=-\frac{3}{4}

x=-\frac{4}{3}

x=-1

There is no possible value for x

x=1

Correct answer:

x=-\frac{3}{4}

Explanation:

Notice how x^4 is the greatest value. This often means that x is negative as (-1)^n=-1 when \dpi{100} n is odd and (-1)^n=1 when \dpi{100} n is even.

Let us examine the first choice, x=-\frac{3}{4}

x^5=-\frac{3^5}{4^5}=-\frac{243}{1024}> -\frac{3}{4}

This can only be true of a negative value that lies between zero and one.

Example Question #2 : How To Find The Square Of An Integer

In the equation above, if  is a positive integer, what is the value of ?

Possible Answers:

Correct answer:

Explanation:

Begin by squaring both sides of the equation:

Now solve for y:

Note that  must be positive as defined in the original question. In this case,  must be 12.

 

 

Example Question #1 : How To Simplify Square Roots

Simplify. Assume all variables are positive real numbers. 

Possible Answers:

Correct answer:

Explanation:

The index coefficent in is represented by . When no index is present, assume it is equal to 2.  under the radical is known as the radican, the number you are taking a root of. 

First look for a perfect square, 

Then to your Variables 

Take your exponents on both variables and determine the number of times our index will evenly go into both. 

So you would take out a  and would be left with a 

*Dividing the radican exponent by the index - gives you the number of variables that should be pulled out.

The final answer would be .

Example Question #4 : Factoring And Simplifying Square Roots

Simplify. Assume all integers are positive real numbers. 

Possible Answers:

Correct answer:

Explanation:

Index of means the cube root of Radican 

Find a perfect cube in    

Simplify the perfect cube, giving you .

Take your exponents on both variables and determine the number of times our index will evenly go into both.

 


The final answer would be

Example Question #4 : Factoring And Simplifying Square Roots

Simplify square roots. Assume all integers are positive real numbers. 

Simplify as much as possible. List all possible answers.

1a.

1b. 

1c. 

Possible Answers:

 and  and 

 and 

 and  and 

 and  and

Correct answer:

 and  and 

Explanation:

When simplifying radicans (integers under the radical symbol), we first want to look for a perfect square. For example, is not a perfect square. You look to find factors of  to see if there is a perfect square factor in , which there is.

1a. 

Do the same thing for .

1b.

1c.Follow the same procedure except now you are looking for perfect cubes. 

Example Question #1 : Simplifying Square Roots

Simplify

÷ √3

Possible Answers:

not possible

2

3√3

3

none of these

Correct answer:

3√3

Explanation:

in order to simplify a square root on the bottom, multiply top and bottom by the root

Asatsimplifysquare_root

Example Question #2 : Simplifying Square Roots

Simplify:

√112

Possible Answers:

4√7

12

20

10√12

4√10

Correct answer:

4√7

Explanation:

√112 = {√2 * √56} = {√2 * √2 * √28} = {2√28} = {2√4 * √7} = 4√7 

Example Question #31 : Basic Squaring / Square Roots

Simplify:

 

√192

Possible Answers:
4√2
8√2
4√3
8√3
None of these
Correct answer: 8√3
Explanation:

√192 = √2 X √96 

√96 = √2 X √48

√48 = √4 X√12

√12 = √4 X √3

√192 = √(2X2X4X4) X √3

        = √4X√4X√4  X √3

        = 8√3

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