GMAT Math : GMAT Quantitative Reasoning

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #2 : Graphing A Two Step Inequality

Capture1

Which of the following inequalities is graphed above?

Possible Answers:

None of the above.

Correct answer:

Explanation:

In order to graph the inequality pictured above, we must first find the equation of its boundary line. Based on the image, we see that the line includes the points  and , so the slope of the line is

.

We can now find the -intercept form of the line by substituting  and the point   into the slope-intercept equation  and solving for :

The equation of the boundary line is therefore . Since we see that the boundary line is dashed, we know that the values on the line are excluded from the inequality, so the  sign will be replaced by a  or a .

In order to determine which one, we can test a point in the solution set; let's test  since it's the simplest to substitute:

 _____

 _____

 _____

, so the correct symbol is 

 

 

 

Example Question #3 : Graphing A Two Step Inequality

Capture2

Which of the following inequalities is graphed above?

Possible Answers:

None of the above.

Correct answer:

Explanation:

In order to graph the inequality pictured above, we must first find the equation of its boundary line. Based on the image, we see that the line includes the points  and , so the slope of the line is

.

We can now find the -intercept form of the line by substituting  and the point   into the slope-intercept equation  and solving for :

The equation of the boundary line is therefore . Since we see that the boundary line is solid, we know that the values on the line are included in the inequality, so the  sign will be replaced by a  or a .

In order to determine which one, we can test a point in the solution set; let's test  :

 _____

 _____

 _____

, so the correct symbol is 

Example Question #4 : Graphing A Two Step Inequality

Capture3

Which of the following inequalities is graphed above?

Possible Answers:

None of the above.

Correct answer:

Explanation:

In order to graph the inequality pictured above, we must first find the equation of its boundary line. Based on the image, we see that the line includes the points  and , so the slope of the line is

.

We can now find the -intercept form of the line by substituting  and the point   into the slope-intercept equation  and solving for :

The equation of the boundary line is therefore . Since we see that the boundary line is dashed, we know that the values on the line are excluded from the inequality, so the  sign will be replaced by a  or a .

In order to determine which one, we can test a point in the solution set; let's test  :

 _____

 _____

 _____

, so the correct symbol is 

Example Question #1 : Algebra

Which equation is linear?

Possible Answers:

x+\Pi y+ez=log(5)

\frac{y+8}{x-2}=x+6

none of them are linear

y=x^{2}-55x+1

Correct answer:

x+\Pi y+ez=log(5)

Explanation:

Let's go through all of the answer choices.

1. x+\Pi y+ez=log(5)\Piand e are both constants, so the equation is actually linear.

2. 5x + 7y - 8yz = 16: This is not linear because of the yz term.  

3. \frac{y+8}{x-2}=x+6: This can be transformed into y + 8 = (x + 6)(x - 2).  Clearly when this is expanded, there will be an x^{2} term, so this is not linear.

4. y=x^{2}-55x+1: This is not linear either, also because of the x^{2} term.

Example Question #2 : Algebra

Solve.

Possible Answers:

Correct answer:

Explanation:

Solve for in the first equation:


Substitute into the second equation:

Solve for .

Example Question #3 : Algebra

What is 

Possible Answers:

Correct answer:

Explanation:

Solve the first equation to get

Substitute that into the second equation and get

Solve the equation to get , then substitute that into the first equation to get .  

Plugging those two values into , gives

  

Example Question #2 : Algebra

Solve the system of equations:

Possible Answers:

The system has no solution.

Correct answer:

The system has no solution.

Explanation:

Multiply both sides of the first equation by 12:

Now, add both sides of the two equations:

Since this is impossible, the system of equations is inconsistent and thus has no solution.

Example Question #4 : Algebra

Give the solution set for .

Possible Answers:

Insufficient information is given to answer the question.

Correct answer:

Explanation:

The expression on the left factors as the difference of squares:

Since , we can substitute:

We now have a system of linear equations to solve:

Example Question #1 : Algebra

A company wants to ship some widgets.  If the weight of the box plus one widget is 6 pounds, and the weight of the box plus two widgets is 10 pounds, then what is the weight of the box and the weight of the widget?  Put the answer in an ordered pair such that the ordered pair is (box weight, widget weight).   

Possible Answers:

Correct answer:

Explanation:

Let the weight of the box be represented by  and the weight of the widget be represented by .  Since the weight of the box plus the weight of one widget is 6 pounds, this can be represented by the equation

 

Since the weight of the box plus two widgets is 10 pounds, this can be represented by the equation

  

We now have two equations and two unknowns and we can now solve for  and .  To do this we solve the first equation for  and substitute it into the second equation.  Solving the first equation for  we get

 

Substituting this into the second equation we get 

 

 

Using  and substituting it into the first equation we get 

 So the weight of the box is 2 pounds and the weight of the widget is 4 pounds.  This gives us the ordered pair .

Example Question #5 : Algebra

Solve for  when

 

 

 

 

Possible Answers:

Correct answer:

Explanation:

Plug in the given value and then isolate .

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