GMAT Math : Algebra

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #1372 : Problem Solving Questions

Consider the incomplete equation

What number replaces the box in order to form an equation with no solution?

Possible Answers:

None of the other choices yields a correct answer.

Correct answer:

None of the other choices yields a correct answer.

Explanation:

Set  to be the number that replaces the box.

Simplify first:

Now solve for  in terms of :

The only possible value of  that might preclude the existence of a solution is , since it makes the denominator 0. However, let us test this value in the original equation:

As it turns out, replacing the box with 15 yields an identity, not a contradiction, so the solution set is the set of all real numbers. There is no number that fits the description.

 

Example Question #291 : Algebra

Consider the incomplete equation

Which of the following numbers can replace the box to form an equation whose one and only solution is 2?

Possible Answers:

None of the other responses gives a correct answer.

Correct answer:

Explanation:

Rewrite this equation as

If 2 is a solution of the equation, then we can substitute 2 for  to make a true arithmetic equation. Replace  with 2 and solve for :

This number replaces the box in order to form the equation

Example Question #291 : Algebra

Solve the following equation for

 

Possible Answers:

Correct answer:

Explanation:

We proceed as follows

 

(Start)

 

(Multiply both sides by 4. Remember to distribute the 4 to both summands on both sides.)

 

(Subtract 28 from both sides)

 

(Subtract 4x from both sides)

 

(Divide both sides by 2)

Example Question #291 : Algebra

Define a function  as follows:

If , evaluate .

Possible Answers:

Correct answer:

Explanation:

Since , we can plug N in for x and 47 in for f(N) to get the following equation, 

From here, we want to solve for N therefore we must isolate N on one side of the equation and all other numbers on the other side.

Example Question #11 : Linear Equations, One Unknown

Lisa went to a bargain bookstore where books were sold for  dollars and magazines for  dollars. After buying six books and four magazines, she only spent $30.00. How much did the books and magazines cost? 

Possible Answers:

Books: $4.20; Magazines: $2.20

Books: $1.80; Magazines: $3.80

Books: $3.80; Magazines: $5.80

Books: $3.80; Magazines: $1.80

Correct answer:

Books: $3.80; Magazines: $1.80

Explanation:

We must first write out the equation to this problem.

  • If we set  to be the cost of books then we can set  to represent the cost of magazines.
  • She purchased  books which means she spent  on books.
  • She also bought  magazines which means she spent  on magazines.
  • The total spent was  so when these two values are added together they must equal  :

 

                       

 

We can now solve for 

Remember: the cost of magazines was  so we must plug in the value to find our answer. 

So, our answer is that books cost $ and magazines cost $

 

Example Question #1376 : Problem Solving Questions

Students at a local college decide to make and sell t-shirts in order to raise money for their activities. They will pay the manufacturer  per t-shirt made and a fixed fee of . If they sell each t-shirt for , how many t-shirts would they have to make and sell to raise ?

Possible Answers:

Correct answer:

Explanation:

We set up the following equation:

The students will need to make and sell 180 t-shirts in order to raise .

Example Question #12 : Solving Linear Equations With One Unknown

Solve for :  

Possible Answers:

Correct answer:

Explanation:

In order to solve for , we must isolate  on one side of the equation:

Example Question #11 : Linear Equations, One Unknown

What is the value of  in the following equation when ?

Possible Answers:

Correct answer:

Explanation:

When solving algebraic equations with one unknown, it is often easier to rearrange the equation first so that you have the unknown variable isolated.

So this:

becomes this when we subtract  from both sides:

Then, divide both sides by  to get  all by itself:

To finish, simply plug in  for  and simplify.

Thus,  is our answer!

Example Question #291 : Algebra

Solve for 

Possible Answers:

Correct answer:

Explanation:

In order to solve for , isolate  on one side of the equation:

Example Question #292 : Algebra

Solve for .

Possible Answers:

Correct answer:

Explanation:

To solve for , we need to isolate  on one side of the equation:

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