Common Factor Extraction Method: Identify the largest free number that we can extract. Then, let's move on to the variables and ask what is the least number of times the X appears in any element? Multiply the free number by the variable the same number of times we have found and we will obtain the greatest common factor.
To verify that you have correctly extracted the common factor, open theparentheses and see if you have returned to the original exercise.
Factoring out the greatest common factor is the first operation we try to carry out when we want to break down an expression into factors. We can remove from the parentheses a factor that is common to both elements and leave inside a simple and comfortable expression. The greatest common factor is the largest factor that is completely common to both elements.
Operation steps for extracting the common factor
Notice which is the largest free number we can extract. Then, let's move on to the unknowns and ask what is the least number of times that X appears in any element? Multiply the free number by the unknown the number of times we have found and we will obtain the greatest common factor. To verify that you have extracted the common factor correctly, open the parentheses and see if you have arrived at the original exercise.
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Test your knowledge
Question 1
\( x^4+2x^2=0 \)
Incorrect
Correct Answer:
\( x=0 \)
Question 2
Solve the following problem:
\( x^7-x^6=0 \)
Incorrect
Correct Answer:
\( x=0,1 \)
Question 3
\( 4x^4-12x^3=0 \)
Solve the equation above for x.
Incorrect
Correct Answer:
\( x=0,3 \)
Let's look at an example of factoring out the common factor from the parentheses.
8x2+4x= Let's see what is the greatest common factor we can take out, the answer is 4. Now let's move on to the variable x. What is the minimum number of times that x appears in any term? The answer is 1. Now let's multiply the common factor obtained by the variable the number of times we have found and it will give us the greatest common factor. That is: 4Ćx=4x Let's take out4x as the common factor and we will obtain: 4x(2x+1) This is our factorization. When we want to find the solutions we will compare it with0 and it will give us: 4x(2x+1)=0 X=0 āāāāāāā2x+1=0 2x=ā1 x=ā1/2 Therefore: x=0,ā1/2
Don't worry, as you practice extracting the common factor you will not need to act according to the operation steps as we taught them, you will do the extraction of the common factor intuitively and quickly.
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Examples and exercises with solutions on factoring by taking out the common factor from the parentheses
Exercise #1
Solve the following problem:
x2āx=0
Video Solution
Step-by-Step Solution
Shown below is the given equation:
x2āx=0
First note that on the left side we are able to factor the expression using a common factor. The largest common factor for the numbers and letters in this case is xand this is due to the fact that the first power is the lowest power in the equation. Therefore it is included both in the term with the second power and in the term with the first power. Any power higher than this is not included in the term with the first power, which is the lowest. Hence this is the term with the highest power that can be factored out as a common factor from all terms in the expression. Continue to factor the expression:
x2āx=0āx(xā1)=0
Proceed to the left side of the equation that we obtained in the last step. There is a multiplication of algebraic expressions and on the right side the number 0. Therefore given that the only way to obtain 0 from a multiplication is to multiply by 0, at least one of the expressions in the multiplication on the left side must equal zero,
Meaning:
x=0ā
or:
xā1=0āx=1ā
Let's summarize then the solution to the equation:
To solve the equation x4+2x2=0, we will use the technique of factoring. Let's proceed step-by-step:
First, notice that both terms x4 and 2x2 have a common factor of x2. We can factor x2 out from the equation:
x2(x2+2)=0
Now, to solve for x, we apply the Zero Product Property, which gives us that at least one of the factors must be zero:
x2=0 or
x2+2=0
Solving the first case, x2=0:
x=0
For the second case, x2+2=0, we reach:
x2=ā2
Since x2=ā2 has no real solutions (squares of real numbers are non-negative), we can conclude that this equation doesn't provide additional real solutions.
Therefore, the only real solution to the given equation is x=0.
The correct choice from the provided options is:
x=0
Answer
x=0
Exercise #3
Solve the following problem:
x7āx6=0
Video Solution
Step-by-Step Solution
Shown below is the given problem:
x7āx6=0
First, note that on the left side we are able factor the expression by using a common factor.
The largest common factor for the numbers and letters in this case is x6due to the fact that the sixth power is the lowest power in the equation . Therefore it is included both in the term with the seventh power and in the term with the sixth power. Any power higher than this is not included in the term with the sixth power, which is the lowest. Hence this is the term with the highest power that can be factored out as a common factor from all terms in the expression. Continue to factor the expression.
x7āx6=0āx6(xā1)=0
Proceed to the left side of the equation that we obtained from the last step. There is a multiplication of algebraic expressions and on the right side the number 0. Therefore due to the fact that the only way to obtain 0 from multiplication is to multiply by 0, at least one of the expressions in the multiplication on the left side must equal zero,
Meaning:
x6=0/6āx=Ā±0x=0ā
(in this case taking the even root of the right side of the equation will yieldtwo possibilities - positive and negative however given that we're dealing with zero, we only obtain one answer)
First, note that on the left side we are able factor the expression by using a common factor. The largest common factor for the numbers and variables in this case is 4x3 due to the fact that the third power is the lowest power in the equation. Therefore it is included in both the term with the fourth power and the term with the third power. Any power higher than this is not included in the term with the third power, which is the lowest. Hence this is the term with the highest power that can be factored out as a common factor for the variables,
For the numbers, note that 12 is a multiple of 4, therefore 4 is the largest common factor for the numbers in both terms of the expression,
Let's continue to factor the expression:
4x4ā12x3=0ā4x3(xā3)=0
Proceed to the left side of the equation that we obtained in the last step. There is a multiplication of algebraic expressions and on the right side the number 0. Therefore given that the only way to obtain 0 from a multiplication is to multiply by 0, at least one of the expressions in the multiplication on the left side must equal zero,
Meaning:
4x3=0/:4x3=0/3āx=0ā
In solving the equation above, we first divided both sides of the equation by the term with the unknown and then extracted a cube root for both sides of the equation.
(In this case, extracting an odd root for the right side of the equation yielded one possibility)
First, note that in the left side we are able to factor the expression by using a common factor. The largest common factor for the numbers and letters in this case is 3x due to the fact that the first power is the lowest power in the equation and therefore is included both in the term with the second power and in the term with the first power. Any power higher than this is not included in the term with the first power, which is the lowest. Therefore this is the term with the highest power that can be factored out as a common factor from all terms for the letters,
For the numbers, note that 9 is a multiple of 3, therefore it is the largest common factor for the numbers in both terms of the expression,
Let's continue to factor the expression:
3x2+9x=0ā3x(x+3)=0
Proceed to the left side of the equation that we obtained in the last step. There is a multiplication of algebraic expressions and on the right side the number 0. Therefore, given that the only way to obtain 0 from a multiplication is to multiply by 0, at least one of the expressions in the multiplication on the left side must equal zero,
Meaning:
3x=0/:3x=0ā
In solving the above equation, we divided both sides of the equation by the term with the variable,