How to find out when an equation has no solution

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GRE Quantitative Reasoning › How to find out when an equation has no solution

1 - 10
1

Quantity A:

Quantity B: 11

Quantity B is greater

CORRECT

Quantity A is greater

0

The two quantities are equal.

0

The relationship cannot be determined.

0

Explanation

Expand out into .

Since , it can be seen that

so Quantity B is greater.

2

Nosol1

There is no solution

CORRECT

3

0

–3

0

1

0

–1/2

0

Explanation

Nosol2

3

Solve:

No Solution

CORRECT

Infinitely Many Solutions

0

0

0

0

Explanation

First, distribute the to the terms inside the parentheses.

Add 6x to both sides.

This is false for any value of . Thus, there is no solution.

4

The sum of two integers is . The larger integer is greater than the smaller integer. What is the positive difference between the two?

CORRECT

0

0

0

Explanation

Let us write down what we are told in mathematical terms, designating the smaller integer as and the larger integer as .

The sum of the two integers is :

And the larger integer is % greater than the smaller integer:

Writing the first equation in terms of gives:

Which allows us to find :

Thus, the positive difference between the two is found as

5

Solve .

No solutions

CORRECT

0

0

0

0

Explanation

By definition, the absolute value of an expression can never be less than 0. Therefore, there are no solutions to the above expression.

6

Quantity A:

Quantity B:

Quantity A is greater.

0

Quantity B is greater.

0

The two quantities are equal.

0

The relationship cannot be determined from the information given.

CORRECT

Explanation

We are given that y = 32. Plug this value of y into the second equation.

32 = x2 – 4

36 = x2

x = +/– 6.

Next find a value for Quantity A:

y/7 = 32/7

This number is less than +6, but more than –6. Thus, the relationship cannot be determined from the information given.

7

Quantity A:

Quantity B:

Quantity A is greater.

CORRECT

Quantity B is greater.

0

The two quantities are the same.

0

The relationship cannot be determined.

0

Explanation

To solve this problem, expand each function described by Quantities A and B:

Quantity A:

Quantity B:

Now note that Quantities A and B only differ in that Quantity A is greater by .

Since we are told that is greater than and thus always positive, Quantity A must be greater than Quantity B for all possible values of .

8

Find the solution to the following equation if x = 3:

y = (4x2 - 2)/(9 - x2)

0

0

6

0

3

0

no possible solution

CORRECT

Explanation

Substituting 3 in for x, you will get 0 in the denominator of the fraction. It is not possible to have 0 be the denominator for a fraction so there is no possible solution to this equation.

9

CORRECT

0

0

0

None of the other answers

0

Explanation

A fraction is considered undefined when the denominator equals 0. Set the denominator equal to zero and solve for the variable.

10

Undefined_denom3

I. x = 0

II. x = –1

III. x = 1

I only

CORRECT

II only

0

III only

0

II and III only

0

I, II, and III

0

Explanation

Undefined_denom2