GMAT Math : Graphing a function

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #122 : Graphing

What is the domain of y = 4 - x^{2}?

Possible Answers:

x \geq 4

all real numbers

x \leq 4

x \leq 0

Correct answer:

all real numbers

Explanation:

The domain of the function specifies the values that  can take.  Here, 4-x^{2} is defined for every value of , so the domain is all real numbers. 

Example Question #1 : Graphing A Function

What is the domain of y=-2\sqrt{x}?

Possible Answers:

x\leq 0

x\geq 0

Correct answer:

x\geq 0

Explanation:

To find the domain, we need to decide which values  can take.  The  is under a square root sign, so  cannot be negative.   can, however, be 0, because we can take the square root of zero.  Therefore the domain is x\geq 0.

Example Question #62 : Graphing

What is the domain of the function y=\sqrt{4-x^{2}}?

Possible Answers:

x\leq -2

Correct answer:

Explanation:

To find the domain, we must find the interval on which \sqrt{4-x^{2}} is defined.  We know that the expression under the radical must be positive or 0, so \sqrt{4-x^{2}} is defined when x^{2}\leq 4.  This occurs when x \geq -2 and x \leq 2.  In interval notation, the domain is .

Example Question #63 : Graphing

Define the functions  and  as follows:

 

What is the domain of the function  ?   

Possible Answers:

Correct answer:

Explanation:

The domain of  is the intersection of the domains of  and and  are each restricted to all values of  that allow the radicand  to be nonnegative - that is, 

, or 

Since the domains of  and  are the same, the domain of  is also the same. In interval form the domain of  is 

Example Question #64 : Graphing

Define 

What is the natural domain of ?

Possible Answers:

Correct answer:

Explanation:

The radical in and of itself does not restrict the domain, since every real number has a real cube root. However, since the expression  is in a denominator, it cannot be equal to zero, so the domain excludes the value(s) for which 

27 is the only number excluded from the domain.

Example Question #65 : Graphing

Define 

What is the natural domain of  ?

Possible Answers:

Correct answer:

Explanation:

Since the expression  is in a denominator, it cannot be equal to zero, so the domain excludes the value(s) for which . We solve for  by factoring the polynomial, which we can do as follows:

Replacing the question marks with integers whose product is  and whose sum is 3:

Therefore, the domain excludes these two values of .

Example Question #66 : Graphing

Define .

What is the natural domain of ?

 

Possible Answers:

Correct answer:

Explanation:

The only restriction on the domain of  is that the denominator cannot be 0. We set the denominator to 0 and solve for  to find the excluded values:

The domain is the set of all real numbers except those two - that is, 

.

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