ISEE Upper Level Quantitative : Variables and Exponents

Study concepts, example questions & explanations for ISEE Upper Level Quantitative

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Example Questions

Example Question #41 : Variables And Exponents

 and  are positive integers greater than 1.

Which is the greater quantity?

(A) 

(B) 

Possible Answers:

It is impossible to determine which is greater from the information given

(A) and (B) are equal

(B) is greater

(A) is greater

Correct answer:

(A) is greater

Explanation:

One way to look at this problem is to substitute . Since  must be positive, and this problem is to compare  and  

and 

Since 2, , and  are positive, by closure, , and by the addition property of inequality,

Substituting back:

(A) is the greater quantity.

Example Question #42 : Variables And Exponents

 and  are positive integers greater than 1.

Which is the greater quantity?

(A) 

(B)  

Possible Answers:

It is impossible to determine which is greater from the information given

(B) is greater

(A) and (B) are equal

(A) is greater

Correct answer:

It is impossible to determine which is greater from the information given

Explanation:

Case 1: 

Then

and  

This makes the quantities equal.

 

Case 2:

Then

and  

This makes (B) greater.

 

Therefore, it is not clear which quantity, if either, is greater.

Example Question #43 : Variables And Exponents

 and  are positive integers greater than 1.

Which is the greater quantity?

(A) 

(B) 

Possible Answers:

(A) and (B) are equal

(B) is greater

(A) is greater

It is impossible to determine which is greater from the information given

Correct answer:

(A) is greater

Explanation:

One way to look at this problem is to substitute . The expressions to be compared are 

and 

Since  is positive, so is , and

Substituting back,

,

making (A) greater.

Example Question #44 : Variables And Exponents

Factor:

Possible Answers:

The expression is a prime polynomial.

Correct answer:

Explanation:

We can rewrite as follows:

Each group can be factored - the first as the difference of squares, the second as a pair with a greatest common factor. This becomes

,

which, by distribution, becomes

Example Question #45 : Variables And Exponents

 is a positive number;  is the additive inverse of .

Which is the greater quantity?

(a) 

(b) 

Possible Answers:

(b) is the greater quantity

(a) is the greater quantity

(a) and (b) are equal

It is impossible to determine which is greater from the information given

Correct answer:

(b) is the greater quantity

Explanation:

If   is the additive inverse of , then, by definition, 

.

, as the difference of the squares of two expressions, can be factored as follows:

Since , it follows that 

Another consequence of  being the additive inverse of  is that

, so

 is positive, so  is as well.

It follows that .

Example Question #1 : How To Divide Exponential Variables

Half of one hundred divided by five and multiplied by one-tenth is __________.

Possible Answers:

10

1

2

5

Correct answer:

1

Explanation:

Let's take this step by step. "Half of one hundred" is 100/2 = 50. Then "half of one hundred divided by five" is 50/5 = 10. "Multiplied by one-tenth" really is the same as dividing by ten, so the last step gives us 10/10 = 1.

Example Question #2 : How To Divide Exponential Variables

Simplify:  

Possible Answers:

Correct answer:

Explanation:

Example Question #46 : Variables And Exponents

Simplify: 

Possible Answers:

Correct answer:

Explanation:

Break the fraction up and apply the quotient of powers rule:

Example Question #4 : How To Divide Exponential Variables

Simplify:

Possible Answers:

Correct answer:

Explanation:

To simplify this expression, look at the like terms separately. First, simplify . This becomes . Then, deal with the . Since the bases are the same and you're dividing, you can subtract exponents. This gives you Since the exponent is positive, you put in the numerator. This gives you a final answer of .

Example Question #5 : How To Divide Exponential Variables

 is a negative number.

Which is the greater quantity?

(a) The reciprocal of 

(b) The reciprocal of 

Possible Answers:

(b) is the greater quantity

(a) and (b) are equal

(a) is the greater quantity

It is impossible to determine which is greater from the information given

Correct answer:

(b) is the greater quantity

Explanation:

A negative number raised to an odd power is negative; a negative number raised to an even power is positive. It follows that  is negative and  is positive. Also, the reciprocal of a nonzero number assumes the same sign as the number itself, so the reciprocal of  is positive and that of  is negative. It follows that the reciprocal of  is the greater of the two.

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