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 #771 : Isee Upper Level (Grades 9 12) Quantitative Reasoning

Define  and  .

Which is the greater quantity?

(A) 

(B) 

 

Possible Answers:

(B) is greater

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

(A) and (B) are equal

(A) is greater

Correct answer:

(B) is greater

Explanation:

Since ,

and 

making (B) greater.

Example Question #101 : Equations

Define  and 

Let  be a positive number. Which is the greater quantity?

(A) 

(B) 

Possible Answers:

(B) is greater

(A) and (B) are equal

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

(A) is greater

Correct answer:

(B) is greater

Explanation:

Regardless of the value of ,

which means that 

.

That is, (B) is greater.

Example Question #101 : Equations

Two lines have -intercept . Line A has -intercept ; Line B has -intercept . Which is the greater quantity?

(A) The slope of Line A

(B) The slope of Line B 

Possible Answers:

(A) is greater

(A) and (B) are equal

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

(B) is greater

Correct answer:

(A) is greater

Explanation:

To get the slope of each line, use the slope formula 

For Line A, . Substitute in the slope formula.

The slope is 

 

For Line B, . Substitute in the slope formula.

The slope is 

 

Since 

,

Line A has the greater slope, and (A) is greater.

 

Example Question #104 : How To Find The Solution To An Equation

Line A has -intercept  and -intercept . Line C has -intercept  and -intercept ; Line B is perpendicular to Line C. Which is the greater quantity?

(A) The slope of Line A

(B) The slope of Line B

Possible Answers:

(A) and (B) are equal

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

(B) is greater

(A) is greater

Correct answer:

(A) and (B) are equal

Explanation:

To get the slope of Line A and Line C, use the slope formula 

For Line A, . Substitute in the slope formula.

The slope is 

 

For Line C, . Substitute in the slope formula.

The slope is 

 

Since Line B is perpendicular to Line C, its slope is the opposite of the reciprocal of that of Line C; this is , which is equal to the slope of Line A.

The two quantities are equal.

Example Question #101 : Algebraic Concepts

One-third of the sum of a number and sixty is ninety-three. What is the number?

Possible Answers:

Correct answer:

Explanation:

If we let  be the number, "the sum of a number and sixty" can be written as 

"One-third of the sum of a number and sixty" can be written as 

Set this equal to ninety-three and solve:

Example Question #106 : How To Find The Solution To An Equation

Twelve added to two-fifths of a number is equal to sixty. What is that number?

Possible Answers:

Correct answer:

Explanation:

If we let  be the number, "two-fifths of a number" can be written as

.

"Twelve added to two-fifths of a number" can be written as

.

Then "Twelve added to two-fifths of a number is equal to sixty" can be written and solved for  as follows:

Example Question #107 : How To Find The Solution To An Equation

Ninety-seven is five less than two-fifths of a number. What is the number?

Possible Answers:

The correct answer is not among the other choices.

Correct answer:

Explanation:

If we let  be the number, "two-fifths of a number" can be written as 

.

"Five less than two-fifths of a number can be written as 

"Ninety-seven is five less than two-fifths of a number" can be written and solved as follows:

Example Question #101 : How To Find The Solution To An Equation

Define  and .

What is the domain of the function  ?

Possible Answers:

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 

Example Question #109 : How To Find The Solution To An Equation

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

For which value of  is the expression  undefined?

 

Possible Answers:

Correct answer:

Explanation:

 , so

This is is undefined if and only if the denominator is equal to zero, which happens when

, or 

Example Question #110 : How To Find The Solution To An Equation

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

For which value of  is the expression  undefined?

Possible Answers:

None of the other responses gives a correct answer.

Correct answer:

None of the other responses gives a correct answer.

Explanation:

, so

This expression is undefined if and only if the denominator is equal to 0. However, for all values of 

, so 

It is impossible for  to be undefined, so none of the four values of  given gives a correct response.

 

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