GMAT Math : Algebra

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #11 : Solving Inequalities

What value of  satisfies both of the following inequalities?

Possible Answers:

Correct answer:

Explanation:

Solve for  in both inequalities:

(1)

Subtract 9 from each side of the inequality:

Then, divide by . Remember to switch the direction of the sign from "less than or equal to" to "greater than or equal to."

(2)

Add  to both sides of the inequality:

Subtract 7 from each side of the inequality:

Divide each side of the inequality by 3:

 

From solving both inequalities, we find  such that:

Only   is in that interval .

 and  are less than 1.33, so they are not in the interval.

 and  are more than 2, so they are not in the interval.

Example Question #2 : How To Find The Solution To An Inequality With Division

Which of the following could be a value of , given the following inequality?

Possible Answers:

Correct answer:

Explanation:

The inequality that is presented in the problem is:

Start by moving your variables to one side of the inequality and all other numbers to the other side:

Divide both sides of the equation by . Remember to flip the direction of the inequality's sign since you are dividing by a negative number!

Reduce:

The only answer choice with a value greater than  is .

Example Question #123 : Algebra

If  and  are two integers, which of the following inequalities would be true?

Possible Answers:

Correct answer:

Explanation:

First let's solve each of the inequalities:

 

 

Don't forget to flip the direction of the sign when dividing by a negative number:

 is the correct answer.  is an integer greater than 3 and  is greater than 9. Therefore, the sum of  and  is greater than 12.

 is not true.  and  are two positive integers as  is greater than 3 and  is greater than 9. The sum of two positive integers cannot be a negative number.

 is not true.  and  are two positive integers as  is greater than 3 and  is greater than 9. The division of two positive numbers is positive and therefore cannot be less than 0.

 is not true.  is greater than 3 and  is greater than 9. The product of  and  cannot be less than 3.

 is not true.  and  are positive. Therefore, the product of  and  is negative and cannot be greater than 0.

Example Question #13 : Solving Inequalities

If an integer  satisfies both of the above inequalities, which of the following is true about ?

Possible Answers:

Correct answer:

Explanation:

First, we solve both inequalities:

 

If  satisfies both inequalities, then  is greater than 5 AND  is greater than 11. Therefore  is greater than 11.

 is the correct answer.

Example Question #1205 : Gmat Quantitative Reasoning

Solve the following inequality:

Possible Answers:

Correct answer:

Explanation:

We start by simplifying our inequality like any other equation:

Now we must remember that when we divide by a negative, the inequality is flipped, so we obtain:

Example Question #1203 : Gmat Quantitative Reasoning

Solve the following inequality:

Possible Answers:

Correct answer:

Explanation:

Solving inequalities is very similar to solving equations, but we need to remember an important rule:

If we multiply or divide by a negative number, we must switch the direction of the inequality. So a "greater than" sign will become a "less than" sign and vice versa.

We are given

Start by moving the  and the  over:

Simplify to get the following:

Then, we will divide both sides of the equation by . Remember to switch the direction of the inequality sign!

So,

Example Question #127 : Algebra

 and . If  the greatest number of the three, then what are the possible values of  ?

Possible Answers:

Correct answer:

Explanation:

The question is equivalent to asking when  and  are both true statements. 

We can solve for  in the first equation:

Now use substitution to solve the inequality

Therefore,  if and only if .

 

Similarly, we can solve for  in the first equation:

Now use substitution to solve the inequality

Therefore,  if and only if .

 

We combine these results, and conclude that both  and  hold - that is,  is the greatest of the three - if and only if .

Example Question #21 : Solving Inequalities

Solve for :

Possible Answers:

Correct answer:

Explanation:

The first step to solving this inequality is to subtract 18 from all three segments of the equation:

8 (- 18)  < -5x + 18 ( - 18) < 103 ( - 18)

-10 < -5x < 85

We then divide the entire equation by -5. According to inequality rules, when we multiply or divide an inequality by a negative number, we must flip the inequality signs.

(-10/-5) > (-5x/-5) > (85/-5)

2 > x > -17 or in conventional layout -17 < x < 2

Example Question #21 : Solving Inequalities

Solve:  

Possible Answers:

 or 

  or  

Correct answer:

Explanation:

In order to solve this inequality, we must split it into two inequalities:

 and 

We then solve each, remembering of course that, when multiplying or dividing by a negative number, we must switch the direction of the inequality sign.

and

Therefore:

Example Question #128 : Algebra

Give the solution set of the inequality

Possible Answers:

Correct answer:

Explanation:

To solve a rational inequality, move all expressions to the left first:

The boundary points of the solution set will be the points at which:

 - that is, ;

;

; that is, .

None of these values will be included in the solution set, since equality is not allowed by the inequality symbol.

Test the intervals

by choosing a value in each interval and testing the truth of the inequality.

: test 

True; include the interval 

 

: test 

False; exclude the interval 

 

: test 

True; include the interval .

 

: test 

False; exclude the interval .

 

The solution set of the inequality is .

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