# GMAT Math : DSQ: Solving linear equations with one unknown

## Example Questions

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### Example Question #11 : Linear Equations, One Unknown . What is ?

(1) (2) Statement 2 alone is sufficient.

Statements 1 and 2 together are not sufficient.

Statement 1 alone is sufficient.

Both statements together are insufficient.

Each statement alone is sufficient.

Each statement alone is sufficient.

Explanation:

Firstly, we should try to find a simplified equation to better see the possible values for . We get . We can see that can either be or .

Statement 1 tells us that the square of is . It follows that must be , therefore, this statement is sufficient.

Statement 2 tells us that the absolute value of is , therefore must be and therefore the statement is also sufficient alone.

Note that it is possible to answer with either statement only because can either be or . If could have been or than statements 1 and 2 would have been insufficient.

### Example Question #931 : Data Sufficiency Questions

What is if, ?

(1) (2) Both statements together are sufficient.

Each statement alone is sufficient.

Statement 2 alone is sufficient.

Statement 1 alone is sufficient.

Statements 1 and 2 together are not sufficient.

Both statements together are sufficient.

Explanation:

To begin with this problem, we should try to solve . It gives us two sets of equations for us to find values for  and . Solving gives us two possible values for  and . Let's see how can the statements help us determine the value of .

Statement 1 gives us an other unknown for the value of . Therefore, this statement is insufficient.

Statement 2 gives an absolute value for this unknown . But we don't know what other values is equal to.

Taken together these statements, allow us to see that must be and therefore are sufficient to answer the question.

### Example Question #932 : Data Sufficiency Questions . What is ?

(1) (2) Statements 1 and 2 together are not sufficient.

Statement 1 alone is sufficient.

Each statement alone is sufficient.

Both statements together are sufficient.

Statement 2 alone is sufficient.

Each statement alone is sufficient.

Explanation:

To approach this problem, we should firstly set up two possible equations for the value of ; either or Statement 1 tells us that is in fact zero. Than the equations return a single value for , therefore statement 1 alone is sufficient.

Statement 2 tells us that , if plug in this value for , we get that: Because there is the absolute value we get two equations:   or     must be 8. Plugging in the value for in our first equation gives us no solution because both sides are of equal value and we end up with .

Therefore, statement 2 alone is sufficient

To conclude, each statement alone is sufficient.

### Example Question #933 : Data Sufficiency Questions

What is ?

(1) (2) Statement 2 alone is sufficient.

Each statement alone is suffcient.

Both statements together are sufficient.

Statements 1 and 2 taken together are not sufficient.

Statement 1 alone is sufficient.

Statements 1 and 2 taken together are not sufficient.

Explanation:

To answer this question, we must find a single value for .

Statement 1 gives us an equation with two possible solutions for . Therefore, statement 1 alone is not sufficient, since can either be or Statemnt 2 alone is also insufficient, because it gives us the same possible values for as the equation in statement 1.

When two statements give us the same the information the answer is either both statements together are sufficient or statements 1 and 2 together are not sufficient. Here neither statement allowed us to answer, it follows that statements 1 and 2 together are not sufficient.

### Example Question #934 : Data Sufficiency Questions , What is ?

(1) (2) Statement 2 alone is sufficient.

Statements 1 and 2 together are not sufficient.

Both statements together are sufficient.

Statement 1 alone is sufficient.

Each statement alone is sufficient.

Both statements together are sufficient.

Explanation:

To find a value for , we should be able to get a value for .

Statement 1 has two unknowns therefore we need another different equation with to be able to find values for these unknowns.

Statement 2 alone is also insufficient because just as statement 1 has two variables and therefore we need more information to solve it.

Taking together these equations, by adding both sides we get and from there we can find a single value for .

Both statements together are sufficient.

### Example Question #935 : Data Sufficiency Questions and is different than . What is ?

(1) (2) is not an integer.

Each statement alone is sufficient.

Both statements together are sufficient.

Statement 1 alone is sufficient.

Statement 2 alone is sufficient.

Statements 1 and 2 together are sufficient.

Statement 1 alone is sufficient.

Explanation:

Firstly we should try to see what are the possible values for , by solving the equations given by the absolute value:

either or .

This allows us to find two values for which are and , let's see how the statements can help us determine a single value for .

Statement 1 tells us that must be greater than one. Only one of our solutions for is greater than one. Therefore, statement 1 alone is sufficient.

Statement 2 tells us that is not an integer, however both solutions are not integer values and therefore statement 2 doesn't help us find a single solution.

Statement 1 alone is sufficient.

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