ISEE Upper Level Math : Equations

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

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Example Questions

Example Question #171 : How To Find The Solution To An Equation

Define .

If , which of the following cannot be a valid definition of ?

Possible Answers:

Correct answer:

Explanation:

, so, substituting 2 for , we see that

.

By definition, 

, so

Substituting and solving for :

Examine all four alternatives by, again, substituting 2 for  in each and finding for which one :

 

 

 

 

Therefore, of the four choices, only  is not a valid definition, since it does not match the conditions.

Example Question #171 : Equations

Define .

If , then which of the following could be the definition of ?

Possible Answers:

Correct answer:

Explanation:

By definition, 

.

Also, by substitution:

Therefore, the question is equivalent to asking for which definition of  it holds that

Each definition in the given choices can be evaluated for  by substitution, with each value of  tested in turn:

 

 

 

 

 

This makes  the correct choice.

 

 

Example Question #172 : Equations

Define .

If , then which of the following could be a valid definition of the function ?

Possible Answers:

Correct answer:

Explanation:

, so, substituting 8 for , we see that

By definition, 

, so

 

Examine all four alternatives by, again, substituting 8 for , and find the one for which.

 

 

 

 

Of the four choices,  is the definition such that .

Example Question #171 : Algebraic Concepts

Solve the following equation for t, when d is 6.

Possible Answers:

Correct answer:

Explanation:

Solve the following equation for t, when d is 6.

Let's begin by plugging 6 in for d and then, using algebra, we will find t.

Divide by 5:

Square root both sides to finish up

Almost there, but because we are square rooting, we need plus or minus the square root of 14

The reason for this is that positive or negative square root of 14 will get us positive 14 when we square it. Therefore, we technically have two answers.

 

Example Question #172 : Algebraic Concepts

Which solution makes this equation true:

Possible Answers:

Correct answer:

Explanation:

To solve for x, we want x to stand alone.  So, we get

Example Question #173 : Algebraic Concepts

Solve the following equation when y is equal to 12.

Possible Answers:

Not enough information provided.

Correct answer:

Explanation:

Solve the following equation when y is equal to 12.

To begin, let's realize that 

So, let's update our original equation.

Now, let's plug in 12 for y

So, what number cubed equals 8?

So our answer is 2

Example Question #174 : Algebraic Concepts

Solve the following equation for q.

Possible Answers:

Correct answer:

Explanation:

Solve the following equation for q.

First, let's divide everything by three. This will work because 147 and 12 are both divisible by 3

 

Now, add 49 to both sides to get the variable by itself

Now, this doesn't come out to a neat decimal, so we will just leave it as is.

Example Question #175 : Algebraic Concepts

Which of the following makes this equation true:

Possible Answers:

Correct answer:

Explanation:

To answer the question, we will need to solve for y.  We get

Example Question #176 : Algebraic Concepts

Solve the following equation for j.

Possible Answers:

No real solutions

Correct answer:

Explanation:

Solve the following equation for j.

We can solve this with basic algebra.

First, add 12 to both sides:

Next, divide both sides by 14

And we end up with...

Example Question #177 : Algebraic Concepts

Which of the following makes the equation true:

Possible Answers:

Correct answer:

Explanation:

To find the answer, we will solve for x. So, we get

 

 

 

 

 

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