ISEE Upper Level Quantitative : How to find the solution to an equation

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

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Example Questions

Example Question #111 : How To Find The Solution To An Equation

Define  and .

Evaluate  .

Possible Answers:

Correct answer:

Explanation:

, so

, so

,

which is the correct response.

Example Question #112 : How To Find The Solution To An Equation

Define  and .

If , evaluate .

Possible Answers:

None of the other responses gives a correct answer.

Correct answer:

Explanation:

Therefore, if 

,

we solve for  in the equation

Example Question #113 : How To Find The Solution To An Equation

For all real numbers  and , define an operation  as follows:

 is a positive number. Which is the greater quantity?

(A) 

(B) 

Possible Answers:

(B) is greater

(A) is greater

(A) and (B) are equal

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

Correct answer:

(A) is greater

Explanation:

Substitute for both in the expression:

The quantities share a denominator that is positve, being one greater than for times a square of a positive. Therefore, we need only compare numerators. For any positive . Therefore,

and 

making (A) greater.

Example Question #114 : How To Find The Solution To An Equation

 and  are both positive.

20 added to four-thirds of  is equal to . 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) is greater

(A) and (B) are equal

Correct answer:

(B) is greater

Explanation:

The statement is equivalent to 

If  is positive, then 

and 

and ,

making (B) greater.

Example Question #115 : How To Find The Solution To An Equation

For all real numbers  and , define an operation  as follows:

 is a positive integer. 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

(A) is greater

(B) is greater

Correct answer:

(B) is greater

Explanation:

Substitute for both in the expression:

Since  is positive, so is common denominator , so we need only compare numerators. Since  must be positive,

and 

making (B) greater.

Example Question #116 : How To Find The Solution To An Equation

 and  are both positive.

20 subtracted from five-sevenths of  is equal to . 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:

The statement is equivalent to 

 or, alternatively,

Since  is positive and , we can derive:

making  greater than . This makes (A) greater.

Example Question #117 : How To Find The Solution To An Equation

Define  and 

What is the domain of the function  ?

Possible Answers:

None of the other responses gives a correct answer.

Correct answer:

None of the other responses gives a correct answer.

Explanation:

  has as its domain the set of values of  for which its radicand is nonnegative; that is,

 or 

 

Similarly,  has as its domain the set of values of  for which its radicand is nonnegative; that is,

 or 

 

The domain of the sum of two functions is the intersection of the domains of the two individual functions. This intersection is 

The domain of  is the single  value , which is not among the choices. 

Example Question #118 : How To Find The Solution To An Equation

Three consecutive integers add up to 36. What is the greatest integer of the three?

Possible Answers:

Correct answer:

Explanation:

To solve this problem, you can translate the question into an equation. It should look like: . Since we don't know the first number, we name it as x. Then, we add one to each following integer, which gives us x+1 and x+2. Then, combine like terms to get . Solve for x and you get 11. However, the question is asking for the greatest integer of the set, so the answer is actually 13 (because it is the x+2 term).

Example Question #119 : How To Find The Solution To An Equation

Column A                     Column B

The value of x in          The value of x in

            

Possible Answers:

The quantity in Column A is greater.

The quantities in both columns are equal.

The quantity in Column B is greater.

The relationship between the columns cannot be determined.

Correct answer:

The quantity in Column A is greater.

Explanation:

First, solve for x in Column A. Subtract 2 from both sides so that . Multiply by 5 on both sides so that X equals 80. Then, solve for x in Column B. Add 3 to both sides so that . X equals 4 in this equation. Therefore, Column A is greater.

Example Question #120 : How To Find The Solution To An Equation

On a 70-question exam, Lisa answered 60 percent correctly. How many answers did she get right?

Possible Answers:

Correct answer:

Explanation:

If Lisa answered 60 percent of the questions on a 70-question exam correctly, the following equation can be used to determine how many quesitons she got right.  is equal to the number of questions she answered correctly. 

Given that , it follows that

Next, we cross multiply, which gives us:

Now, we divide each side by 5, resulting in:

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