Symmetry

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College Algebra › Symmetry

Questions 1 - 10
1

Relation

The above table refers to a function with domain .

Is this function even, odd, or neither?

Neither

Even

Odd

Explanation

A function is odd if and only if, for every in its domain, ; it is even if and only if, for every in its domain, .

We see that and . Therefore, , so is false for at least one . cannot be even.

For a function to be odd, since , it follows that ; since is its own opposite, must be 0. However, ; cannot be odd.

The correct choice is neither.

2

Define .

Is this function even, odd, or neither?

Neither

Odd

Even

Explanation

A function is odd if and only if, for all , ; it is even if and only if, for all , . Therefore, to answer this question, determine by substituting for , and compare it to both and .

, so is not even.

, so is not odd.

3

Consider the function .

Is an even function, an odd function, or neither?

Even

Odd

Neither

Explanation

A function is even if, for each in its domain,

.

It is odd if, for each in its domain,

.

Substitute for in the definition:

Since , is an even function.

4

is an even function; .

True or false: It follows that .

False

True

Explanation

A function is even if and only if, for all in its domain, . It follows that if , then

.

No restriction is placed on any other value as a result of this information, so the answer is false.

5

Untitled

Which of the following is true of the relation graphed above?

It is an odd function

It is an even function

It is a function, but it is neither even nor odd.

It is not a function

Explanation

The relation graphed is a function, as it passes the vertical line test - no vertical line can pass through it more than once, as is demonstrated below:

Untitled

Also, it can be seen to be symmetrical about the origin. Consequently, for each in the domain, - the function is odd.

6

is a piecewise-defined function. Its definition is partially given below:

How can be defined for negative values of so that is an odd function?

cannot be made odd.

Explanation

, by definition, is an odd function if, for all in its domain,

, or, equivalently

One implication of this is that for to be odd, it must hold that . If , then, since

for nonnegative values, then, by substitution,

This condition is satisfied.

Now, if is negative, is positive. it must hold that

,

so for all

,

the correct response.

7

Relation

Which of the following is true of the relation graphed above?

It is an odd function

It is an even function

It is not a function

It is a function, but it is neither even nor odd.

Explanation

The relation graphed is a function, as it passes the vertical line test - no vertical line can pass through it more than once, as is demonstrated below:

Relation

Also, it is seen to be symmetric about the origin. Consequently, for each in the domain, - the function is odd.

8

is an even function. Let .

Is an even function, an odd function, or neither?

Odd

Even

Neither

Explanation

A function is even if, for each in its domain,

.

It is odd if, for each in its domain,

.

Substitute for in the definition of :

Since is even, , so

This makes an odd function.

9

Which of the following is symmetrical to across the origin?

Explanation

Symmetry across the origin is symmetry across .

Determine the inverse of the function. Swap the x and y variables, and solve for y.

Subtract 3 on both sides.

Divide by negative two on both sides.

The answer is:

10

Determine the symmetry of the following equation.

Does not have symmetry.

Symmetry along the x-axis.

Symmetry along the origin.

Symmetry along the y-axis.

Symmetry along all axes.

Explanation

To check for symmetry, we are going to do three tests, which involve substitution. First one will be to check symmetry along the x-axis, replace .

This isn't equivilant to the first equation, so it's not symmetric along the x-axis.

Next is to substitute .

This is not the same, so it is not symmetric along the y-axis.

For the last test we will substitute , and

This isn't the same as the orginal equation, so it is not symmetric along the origin.

The answer is it is not symmetric along any axis.

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