Writing inequalities - Algebra 1

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Question

Write an inequality that represents the following number line.

Line

Answer

On the number line, the graph starts at –1 and ends at 3.

The line runs between –1 and 3, so we know our inequality involves only values of x that fall between these two numbers. The open circle at –1 indicates that –1 is not included, while the shaded circle on 3 indicates that 3 is included.

Combining these two inequalities into one give us our answer.

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Question

At a fair, there is a game where players step on a scale and weigh themselves. The objective of the game is for the host to guess the player's weight. A player loses if the host of the game can guess the player's weight within pounds, inclusive. Suppose a player weighs pounds. Write an inequality that represents the range of numbers such that the player loses. (Let represent the guess weight.)

Answer

For the player to lose, the host has to guess within pounds of the player's weight, inclusive. Thus, the host can guess any number between pounds and pounds ; that is, if is the weight the host guesses, then , which translates to .

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Question

Write a compound inequality that describes the given graph:Or_open

Answer

The graph shows an arrow beginning on 5 with an open circle and pointing to the left, thus that portion of the graph says, all real numbers less than 5. There is a second arrow beginning on 9 with a closed circle and pointing to the right, representing all real numbers greater than or equal to 9. Since we are joining the two parts of the graph, we have a compound inequality utilizing the "or" statement. So our answer is .

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Question

Solve for :

Answer

The first step is to distribute (multiply) through the parentheses:

Then subtract from both sides of the inequality:

Next, subtract the 12:

Finally, divide by two:

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Question

A candy company is inspecting its factory. In a standard bag of candy there are a minimum of 14 individual candies, and a maximum of 22. Let be the number of candies in a standard bag. Write an expression for using inequalities.

Answer

In terms of inequalities, we know two things. is greater than or equal to 14 (which is the same as being greater than 13). And we know is less than or equal to 22 (which is the same as being less than 23).

So, we have to find the correct statement where we can find the two inequalities. We see we need and .

Therefore the only answer that fits our needs is .

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Question

Write as an algebraic inequality:

Twenty subtracted from the product of seven and a number exceeds one hundred.

Answer

"The product of seven and a number " is . "Twenty subtracted from the product of seven and a number" is . "Exceeds one hundred" means that this is greater than one hundred, so the correct inequality is

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Question

Write as an algebraic inequality:

Twice the sum of a number and sixteen is no less than sixty.

Answer

"The sum of a number and sixteen" is translates to ; twice that sum is . " Is no less than sixty" means that this is greater than or equal to sixty, so the desired inequality is

.

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Question

Write as an algebraic inequality:

Twice the sum of a number and sixteen does not exceed eighty.

Answer

"The sum of a number and sixteen" translates to ; twice that sum is . "Does not exceed eighty" means that it is less than or equal to eighty, so the desired inequality is

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Question

Find the solution set of the inequality:

Answer

or, in interval notation,

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Question

Find the solution set of the inequality:

Answer

or, in interval notation,

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Question

Solve the inequality.

Answer

To solve , it is necessary to isolate the variable and the integers.

Subtract and from both sides of the equation.

Divide by nine on both sides.

This answer is also the same as:

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Question

Choose the correct mathematical expression of the sentence,"A number is less than or equal to seventeen."

Answer

Choose the correct mathematical expression of the sentence,"A number is less than or equal to seventeen."

This sentence contains the phrase "less than or equal to." This means that we need to write an inequality. When writing inequalities, always remeber that the pointed end points to the smaller of the two values.

So, we have "A number ..."

"...is less than or equal to..."

See how the inequality sign has the pointy end facing the ? The pointy end should always face the smaller of the two values, and the open end should always face the larger of the two values. I was always taught that the inequality sign is like a hungry alligator. It always wants to eat the larger number!

Anyway,"...seventeen"

So we have our inequality. Note the horizontal line in the inequality sign. That is where we get the "...or equal to..." part.

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Question

How would you write the equations: "I can spend no more than dollars when I go to the store today."

Answer

The way the sentence is phrased suggests that the person can spend up to dollars but not a penny more. This suggests that , the amount spend can be but not exceed it.

So your answer is:

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Question

Given the following problem, write the inequality.

Seven less than two times a number is greater than fourteen.

Answer

Seven less than two times a number is greater than fourteen.

Let's look at the problem step by step.

If we do not know the value of a number, we give it a variable name. Let's say x. So, we see in the problem

Seven less than two times a number is greater than fourteen.

So, we will replace a number with x.

Seven less than two times x is greater than fourteen.

Now, we see that is says "two times" x, so we will write it like

Seven less than 2 x is greater than fourteen.

The problem says "seven less" than 2x. This simply means we are taking 2x and subtracting seven. So we get

2x - 7 is greater than fourteen

We know the symbol for "is greater than". We can write

2x - 7 > fourteen

Finally, we write out the number fourteen.

2x - 7 > 14

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Question

Express the following as an inequality:

Bob's amount of apples () is more than twice the amount of Adam's bananas ().

Answer

To solve, you must convert the statement into an expression. The key work is "is". Whatever is on the left of that in the sentence will be on the left side of the expression. The same goes for the right. Thus, is on the left and is on the right.

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Question

Write the following as a mathematical inequality:

A number is less than or equal to three times the sum of another number and five

Answer

Write the following as a mathematical inequality:

A number is less than or equal to three times the sum of another number and five.

Let's begin with

"A number" let's call it x

"...is less than or equal to..."

So far we have:

Now,

"...three times..."

"...the sum of another number and five."

So, all together:

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Question

Write an inequality for the following statement:

Two times the sum of and is greater than half of the product of and .

Answer

When writing statments as inequalities, you must take it one step at a time. So in the statement

Two times the sum of and is greater than half of the product of and .

we will rewrite it one part at a time.

Two times the sum of and is greater than half of the product of and .

times the sum of and is greater than half of the product of and .

the sum of and is greater than half of the product of and .

is greater than half of the product of and .

half of the product of and .

of the product of and .

Simplify.

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Question

The admission for a carnival ride requires kids to be more than 40 inches tall, and no greater than 70 inches. Write the inequality.

Answer

In order to write the inequality, we must find the key words in the sentence.

Write the equations from the following key words. Let be the height.

More than 40 inches tall:

No greater than 70 inches:

No greater than a certain height means it can be at that height, but cannot be greater than the given height.

The inequalities can be combined to a compound inequality:

The answer is:

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Question

Write the inequality:

Two less than twice a number is less than two.

Answer

Break up the statement by parts. Let that number be .

Twice a number:

Two less than twice a number:

Less than two:

Combine the parts.

The answer is:

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Question

Write the inequality: Three less than twice a number is more than three times the number.

Answer

Break up the sentence into parts. Let the number be .

Twice a number:

Three less than twice a number:

Three less than twice a number is more than:

Three times the number:

Combine the terms to form the inequality.

The answer is:

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