The solution for an equation is a numerical value that, when inserted in the place of the unknown (or the variable), will render both members of the equation equal, that is, we will obtain a "true statement". In first degree equations with one unknown, there can only be one solution.

Example:

X1=5X - 1 = 5

Solution of an equation x-1=5

This is an equation with one unknown or variable indicated by the letter XX. The equation is composed of two members separated by the use of the equal sign = = . The left member is everything to the left of the sign = = , and the right member is everything to the right of the sign.

Our goal is to isolate the variable (or clear the variable) X X in order that it only remains in one of the members of the equation. In doing so we should be able to determine its value. In this article we will learn how to use the four mathematical operations(addition, subtraction, multiplication and division) to isolate the variable X X .

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Test yourself on linear equations!

einstein

Solve the equation

\( 5x-15=30 \)

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In this article we will get to know the equations and learn simple ways to solve them.


We will now look at equations with only one unknown

For example

Let's go back to the equation of the previous example:

X1=5X-1 = 5

We want to isolate XX. To do this we will add 11 to both members of the equation.

We will write it like this:

X1=5X-1 = 5

We obtain the following:

x1+1=5+1x-1 + 1 = 5 + 1

That is:

X=6X = 6

This is the solution to our equation. We can always check if we are correct by inserting our answer into the original equation. Let's placeX=6 X=6 into the equation

X1=5X-1 = 5

and we obtain the following

61=5 6-1 = 5

5=55=5

This is a true statement, 55 really equals 55, i.e., our solution is correct.


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Another example

Z+7=15Z + 7 = 15

Upon observation we can see that the variable in this equation is ZZ. The variable can be denoted by any letter we want.

As we have explained before, we are interested in finding the value of the ZZ that will give us the solution to the equation. Therefore, we will now try to isolate ZZ. We will do this by subtracting 77 from the two members of the equation.

It looks like this:

Z+7=15Z + 7 = 15

We will obtain the following:

Z+77=157Z + 7 -7 = 15 – 7

Z=8Z = 8

This is the solution to the equation. It's always a good idea to check if we have found the correct value of the unknown by placing our answer into the original equation.

Let's remember what the original equation was:

Z+7=15Z + 7 = 15

let's put

Z=8Z = 8

and we should obtain:

8+7=158 + 7 = 15

15=1515=15

This is indeed a true statement, i.e., the answer is correct.


Solving equations by applying multiplication and division operations

So far we have solved equations by applying addition and subtraction operations to both sides of the equation. Now we will observe further examples of equations that we can solve with multiplication and division operations:

Do you know what the answer is?

Exercise 1

Determine the value of the unknown in the following equation and check whether it is correct.

2X=82X = 8

We want to isolate the XX. We divide both members of the equation by 22. We will write it as follows :

2X/2=8/22X/2= 8/2

and we should obtain :

X=4X = 4

It is a good idea to place the solution into the original equation to check if our solution is correct:

2×4=82\times 4 = 8

8=88 = 8

This is indeed a true statement, i.e., the answer is correct.


Exercise 2

Determine the value of the unknown in the following equation and verify that it is correct.

3Y=18-3Y = 18

In order to isolate the variable Y we divide both members of the equation by 3 -3

3Y/3=18/3-3Y/-3 = 18/-3

Y=6Y = -6

To verify our result, it is a good idea to insert it back into the original equation. Try it!


Check your understanding

Exercise 3

Determine the value of the unknown in the following equation and verify that it is correct.

13x=5\frac{1}{3}x=5

Here we have a fraction in the equation. Our goal is to remove it and to isolate the X X . We multiply both members of the equation by. 3 3

3×13x=3×53\times\frac{1}{3}x=3\times5

We obtain the following:

x=15x=15

To verify this we will insert the obtained result into the original equation:

13×15=5\frac{1}{3}\times 15=5

5=55=5

This is indeed a true statement, i.e., the answer is correct.


Exercise 4

Determine the value of the unknown in the following equation and check that it is correct.

2x+3=52x + 3 = 5

This exercise requires both subtraction and division operations. First, we subtract 3 3 from the two members of the equation:

2x+3=52x + 3 = 5

2x+33=532x + 3 - 3 = 5 – 3

2x=22x = 2

Now we will divide the two members of the equation by. 2 2 and we obtain the following:

2x/2=2/22x/2 = 2/2

X=1X = 1

Let's insert the obtained result into the original equation to check if we have done it correctly:

2×1+3=52\times 1 + 3 = 5

5=55 = 5

This is indeed a true statement, i.e., the answer is correct.


Do you think you will be able to solve it?

Exercise 5

Determine the value of the unknown in the following equation and verify that it is correct.

​​​​​​​X6=0​​​​​​​X-6=0

This exercise contains an addition operation 6 6 in both members of the equation, so we have:
​​​​​​​X6+6=0+6​​​​​​​X-6+6=0+6

After simplifying the expression we obtain the solution to the equation X=6X=6 Due to the fact that if we insert 66 instead of the XX we will obtain the result 00 on both sides of the equation resulting in two equivalent members.


Exercise 6

Determine the value of the unknown in the following equation and verify that it is correct.

2X6=02X-6=0

This exercise is comprised of an addition operation 6 6 in both members of the equation, as follows:

2X6+6=0+62X-6+6=0+6

2X=62X=6

Now we proceed to divide by 2 2 on both sides of the equation :

2X/2=6/22X/2=6/2

X=3X=3

The solution of the equation is X=3X=3 due to the fact that if we insert 33 in the place of the XX we should obtain the result 00 on both sides of the equation, resulting in two equivalent members.


Test your knowledge

Exercise 7

Determine the value of the unknown in the following equation and check that it is correct.

3X5=163X-5=16

This exercise requires us to add 5 5 to both members of the equation, so we have the following:

3X5+5=16+53X-5+5=16+5

3X=213X=21

Now we divide both sides of the equation by 3 3 :

3X/3=21/33X/3=21/3

X=7X=7

The solution of the equation is X=7X=7 due to the fact that if we insert 77 in the place of XX we will obtain the result 1616 on both sides of the equation, resulting in two equivalent members.


Questions on the subject

How to clear an unknown?

Isolating the variable with mathematical operations.


Do you know what the answer is?

How to isolate a variable or unknown?

Passing like terms to each side of the equation and performing mathematical operations.


How to corroborate the solution of an equation?

Substituting the value found in the original equation and verifying that the statement of equality is satisfied.


Check your understanding

What is an unknown?

It is the unknown value of the equation.


How to solve a first order equation with one unknown?

Isolating the variable with mathematical operations.


Do you think you will be able to solve it?

What is a first order equation with one unknown?

It is a mathematical statement of equality involving a variable raised to the first power and fixed values that are numbers.


Test your knowledge

Examples with solutions for Linear Equations

Exercise #1

Solve the equation

5x15=30 5x-15=30

Video Solution

Step-by-Step Solution

We start by moving the sections:

5X-15 = 30
5X = 30+15

5X = 45

 

Now we divide by 5

X = 9

Answer

x=9 x=9

Exercise #2

4x:30=2 4x:30=2

Video Solution

Step-by-Step Solution

To solve the given equation 4x:30=2 4x:30 = 2 , we will follow these steps:

  • Step 1: Recognize that 4x:304x:30 implies 4x30=2\dfrac{4x}{30} = 2.

  • Step 2: Eliminate the fraction by multiplying both sides of the equation by 30.

  • Step 3: Simplify the equation to solve for xx.

Now, let's work through each step:

Step 1: The equation is written as 4x30=2\dfrac{4x}{30} = 2.

Step 2: Multiply both sides of the equation by 30 to eliminate the fraction:
30×4x30=2×30 30 \times \dfrac{4x}{30} = 2 \times 30

This simplifies to:
4x=60 4x = 60

Step 3: Solve for xx by dividing both sides by 4:
x=604=15 x = \dfrac{60}{4} = 15

Therefore, the solution to the problem is x=15 x = 15 .

Checking choices, the correct answer is:

x=15 x = 15

Answer

x=15 x=15

Exercise #3

Solve the equation

7x+5.5=19.5 7x+5.5=19.5

Video Solution

Step-by-Step Solution

To solve the given equation 7x+5.5=19.5 7x + 5.5 = 19.5 , we'll follow these steps:

  • Step 1: Eliminate the constant term from the left side by subtracting 5.5 from both sides of the equation.
  • Step 2: Simplify the equation after subtraction to isolate the term with x x .
  • Step 3: Use division to solve for x x .

Now, let's work through each step:

Step 1: Subtract 5.5 from both sides.

We have:
7x+5.55.5=19.55.5 7x + 5.5 - 5.5 = 19.5 - 5.5

This simplifies to:
7x=14 7x = 14

Step 2: Divide both sides by 7 to solve for x x .

So, we divide by 7:
7x7=147 \frac{7x}{7} = \frac{14}{7}

This simplifies to:
x=2 x = 2

Therefore, the solution to the problem is x=2 x = 2 .

Answer

x=2 x=2

Exercise #4

Solve the equation

20:4x=5 20:4x=5

Video Solution

Step-by-Step Solution

To solve the exercise, we first rewrite the entire division as a fraction:

204x=5 \frac{20}{4x}=5

Actually, we didn't have to do this step, but it's more convenient for the rest of the process.

To get rid of the fraction, we multiply both sides of the equation by the denominator, 4X.

20=5*4X

20=20X

Now we can reduce both sides of the equation by 20 and we will arrive at the result of:

X=1

Answer

x=1 x=1

Exercise #5

Solve the equation

8x10=80 8x\cdot10=80

Video Solution

Step-by-Step Solution

To solve this linear equation, we need to isolate the variable x x . Here are the steps to follow:

  • Step 1: Simplify the equation by dividing both sides by 10. This gives us:

8x1010=8010 \frac{8x \cdot 10}{10} = \frac{80}{10}

This simplifies to:

8x=8 8x = 8

  • Step 2: Now, isolate x x by dividing both sides by 8:

8x8=88 \frac{8x}{8} = \frac{8}{8}

This simplifies to:

x=1 x = 1

Therefore, the solution to the equation 8x10=80 8x \cdot 10 = 80 is

x=1 x = 1 .

Answer

x=1 x=1

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