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Linear Expressions

Linear Expressions

Did you know that a number of real-life problems that contain unknown quantities could be modeled into mathematical statements to help solve them easily? In this article, we are going to discuss linear expressions, what they look like, and how to solve them.

What are linear expressions?

Linear expressions are algebraic expressions containing constants and variables raised to the power of 1.

For example, is a linear expression because the variable here is also a representation of . The moment there is such a thing as , it ceases to be a linear expression.

Here are some more examples of linear expressions:

1.

2.

3.

What are variables, terms, and coefficients?

Variables are the letter components of expressions. These are what differentiate arithmetic operations from expressions. Terms are the components of expressions that are separated by addition or subtraction, and coefficients are the numerical factors multiplying variables.

For example, if we were given the expression, x and y could be identified as the variable components of the expression. The number 6 is identified as the coefficient of the term. The numberis called a constant. The identified terms here are and.

We can take a few examples and categorize their components under either variables, coefficients, or terms.

Variables
Coefficients
Constants
Terms
x and y
-3
x
-4
2
x and y
1 (though it's not shown, this is technically the coefficient of xy)
Variables are what differentiate expressions from arithmetic operations

Writing linear expressions

Writing linear expressions involves writing the mathematical expressions out of word problems. There are mostly keywords that help out with what kind of operation to be done when writing an expression from a word problem.

OperationAdditionSubtractionMultiplicationDivision
KeywordsAdded toPlusSum ofIncreased byTotal ofMore thanSubtracted fromMinusLess thanDifferenceDecreased byFewer thanTake awayMultiplied byTimesProduct ofTimes ofDivided byQuotient of
We can go ahead to take examples of how this is done.

Write the phrase below as an expression.

more than a number

Solution:

This phrase suggests that we add. However, we need to be careful about the positioning. 14 more than means 14 is being added to a certain number.

Write the phrase below as an expression.

The difference of 2 and 3 times a number.

Solution:

We should look out for our keywords here, "difference" and "times". "Difference" means we will be subtracting. So we are going to subtract 3 times a number from 2.

Simplifying linear expressions

Simplifying linear expressions is the process of writing linear expressions in their most compact and simplest forms such that the value of the original expression is maintained.

There are steps to follow when one wants to simplify expressions, and these are;

  • Eliminate the brackets by multiplying the factors if there are any.

  • Add and subtract the like terms.

Simplify the linear expression.

Solution:

Here, we will first operate on the brackets by multiplying the factor (outside the bracket) by what is in the brackets.

We will add like terms.

This means that the simplified form of is, and they possess the same value.

Linear equations are also forms of linear expressions. Linear expressions are the name that covers linear equations and linear inequalities.

Linear equations

Linear equations are linear expressions that possess an equal sign. They are the equations with degree 1. For example, . Linear equations are in standard form as

where andare coefficients

andare variables.

is constant.

However, is also known as the x-intercept, whilst the is also the y-intercept. When a linear equation possesses one variable, the standard form is written as;

where is a variable

is a coefficient

is a constant.

Graphing linear equations

As mentioned earlier that linear equations are graphed in a straight line, it is important to know that with a one-variable equation, linear equation lines are parallel to the x-axis because only the x value is taken into consideration. Lines graphed from two-variable equations are placed where the equations demand that it is placed, although still straight. We can go ahead and take an example of a linear equation in two variables.

Plot the graph for the line .

Solution:

First, we will convert the equation into the form .

By this, we can know what the y-intercept is too.

This means we will make y the subject of the equation.

Now we can explore the y values for different values of x as this is also considered as the linear function.

So take x = 0

This means we will substitute x into the equation to find y.

y = -1

Take

y = 0

Take x = 4

y = 1

What this actually means is that when

x = 0, y = -1

x = 2, y = 0

x = 4, y = 1

and so on.

We will now draw our graph and indicate the x and y-axis are.

After which we will plot the points we have and draw a line through them.

Linear expressions, Graphing, StudySmarterGraph of line x - 2y = 2

Solving Linear equations

Solving linear equations involve finding the values for either x and/or y in a given equation. Equations could be in a one-variable form or a two-variable form. In the one variable form,, representing the variable is made the subject and solved algebraically.

With the two-variable form, it requires another equation to be able to give you absolute values. Remember in the example where we solved for the values of, when. And when , . This means that as long as was different, was going to be different too. We can take an example into solving them below.

Solve the linear equation

Solution:

We will solve this by substitution. Makethe subject of the equation in the first equation.

Substitute it into the second equation

y = 1

Now we can substitute this value of y into one of the two equations. We will choose the first equation.

This means that with this equation, when

This can be evaluated to see if the statement is true

We can substitute the values of each variable found into any of the equations. Let us take the second equation.

This means that our equation is true if we saywhen .

Linear Inequalities

These are expressions used to make comparisons between two numbers using the inequalities symbols such as . Below, we will look at what the symbols are and when they are used.

Symbol nameSymbolExample
Not equal
Less than<
Greater than>
Less than or equal to
Greater than or equal to

Solving Linear Inequalities

The primary aim of solving inequalities is to find the range of values that satisfy the inequality. This mathematically means that the variable should be left on one side of the inequality. Most of the things done to equations are done to inequalities too. Things like the application of the golden rule. The difference here is that some operative activities can change the signs in question such that < becomes >, > becomes <, ≤ becomes ≥, and ≥ becomes ≤. These activities are;

  • Multiply (or divide) both sides by a negative number.

  • Swapping sides of the inequality.

Simplify the linear inequality and solve for.

Solution:

You first need to add 3 to each side,

Then divide each side by 4.

The inequality symbol remains in the same direction.

Any number 6 or greater is a solution to the inequality.

Linear Expressions - Key takeaways

  • Linear expressions are those statements that each term that is either a constant or a variable raised to the first power.
  • Linear equations are the linear expressions that possess the equal sign.
  • Linear inequalities are those linear expressions that compare two values using the <, >, ≥, ≤, and ≠ symbols.

Frequently Asked Questions about Linear Expressions

Linear expressions are those statements that each term is either a constant or a variable raised to the first power. 

Group the like terms, and add them such that terms with the same variables are added, and constants are also added.

Step 1: Group the first two terms together and then the last two terms together. 

Step 2: Factor out a GCF from each separate binomial. 

Step 3: Factor out the common binomial. Note that if we multiply our answer out, we do get the original polynomial. 


However, linear factors appear in the form of ax + b and cannot be factored further. Each linear factor represents a different line that, when combined with other linear factors, result in different types of functions with increasingly complex graphical representations.

There are no particular formulas for solving linear equations. However, linear expressions in one variable are expressed as;

 ax + b, where, a ≠ 0 and x is the variable.

Linear expressions in two variables are expressed as;

ax + by  + c

The addition/subtraction rule and the multiplication/division rule.

Final Linear Expressions Quiz

Question

What is the standard form of linear equations?

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Answer

 y  = mx + b

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Question

What is m in the standard form of linear equations?

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Answer

The slope of the line

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Question

Given two points, what is the first thing to do to find the equation of a line?

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Answer

Find the slope of the line

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Question

What does b represent in the standard form of a linear equation?

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Answer

y-intercept

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Question

The gradient is also known as

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Answer

Slope

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Question

What is the slope of the line given two points as (2, 3) and (-1, -2)

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Answer

3

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Question

Write the slope of the line with points (2, 3) and (-1, -2) 

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Answer

y = 3x -3

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Question

Write an equation for the word problem: A city parking garage charges a flat rate of $3.00 for parking 2hours or less, and $0.50per hour for each additional hour. Write a linear model that gives the total charge in terms of additional hours parked.

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Answer

y = 0.50x + 3


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Question

One-dimensional equations are also known as ____

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Answer

Linear equations

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Question

What are linear equations?

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Answer

Linear equations are equations that have the highest power of the variable is always 1

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Question

What is the standard form of linear equations in one variable?

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Answer

ax + b = 0

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Question

What is the standard form for linear equations in two variables?

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Answer

ax + by = c

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Question

How many equations are needed to solve linear equations in one variables to have absolute values as solutions?

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Answer

One

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Question

How many equations are needed to solve linear equations in two variables to have absolute values as solutions?


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Answer

2

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Question

What is the value of x in the equation 2x + 5 = 15?

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Answer

x = 5

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Question

Find x if 5 - x = 12

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Answer

x = -7

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Question

What is the value of x in the equation (2x + 5)/(x + 4) = 1 

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Answer

x = -1

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Question

Solve 6x - 19 = 3x - 10


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Answer

x = 3

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Question

What are linear expressions?

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Answer

Linear expressions are those statements that each term that is either a constant or a variable raised to the first power. 

Show question

Question

Which of these is a linear expression?

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Answer

3x = 4

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Question

What is a linear equation?

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Answer

Linear equations are linear expressions that equate one item to another. Apparently, have = in their expressions

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Question

What is linear inequality?

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Answer

These are expressions used to make comparisons between two numbers using the inequalities symbols such as <, >, ≠ . 

Show question

Question

State whether the statement here is a linear equation or an inequality.

3x + 1 > 9 - 3(2)

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Answer

Linear inequality

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Question

State whether the statement here is a linear equation or an inequality.

 x - 6 = 12


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Answer

Linear equation

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Question

What does > symbol mean?

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Answer

The quantity before the symbol is greater than that after the symbol

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Question

Solve 3 = 2x + 1

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Answer

x = 1

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Question

Solve for 5x = 6 + 4

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Answer

x = 2

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Question

Solve -2x - 39 ≥ -15


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Answer

x ≤ -12 

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Question

What are inequalities in Maths?

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Answer

Inequalities are algebraic expressions that instead of representing how both sides of an equation are equal to each other, represent how one term is less than, less than or equal, greater than, or greater than or equal than the other.

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Question

What are the four symbols used in inequalities?

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Answer

Less than (<), less than or equal to (), greater than (>), and greater than or equal to ().

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Question

What are linear inequalities?

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Answer

Linear inequalities are inequalities where the maximum exponent present in its variables is power 1. 

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Question

What is the solution of an inequality?

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Answer

The solution of an inequality is the set of all real numbers that make the inequality true. Therefore, any value of x that satisfies the inequality is a solution for x.

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Question

What symbols exclude the specific value as part of the solution?

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Answer

The symbols > (greater than) and < (less than) exclude the specific value as part of the solution.

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Question

How do you represent on the number line that the value of x is not part of the solution?

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Answer

With an open dot

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Question

How do you represent on the number line that the value of x is not part of the solution?

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Answer

With a closed dot

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Question

What do you need to do if you multiply or divide the inequality by a negative number?

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Answer

Reverse the symbol of the inequality

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Question

What are compound inequalities?

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Answer

Compound inequalities are two inequalities joined together by the words and or or.

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Question

How do you solve compound inequalities?

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Answer

The steps to solve compound inequalities are as follows:

  1. Separate the compound inequality into its component inequalities.
  2. Solve each inequality separately.
  3. Combine the results from step 2 into a new compound inequality. (This step applies only to AND compound inequalities).
  4. Graph the solution on the number line.

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