How do you factor $ 8{{x}^{3}}+1 $ ?
Answer
629.1k+ views
Hint: In the problem we have to factorize $ 8{{x}^{3}}+1 $ . So first we will factorize the coefficient of the $ {{x}^{3}} $ by checking the numbers which will divide the number $ 8 $ by giving zero reminder. Now we will use the exponential formula $ {{a}^{m}}{{b}^{m}}={{\left( ab \right)}^{m}} $ , we will simplify the term $ 8{{x}^{3}} $ . We know that $ {{1}^{n}}=1 $ , so we will use $ n=3 $ for this problem. Now the total equation is converted in the from of $ {{a}^{3}}+{{b}^{3}} $ . We have the formula $ {{a}^{3}}+{{b}^{3}}=\left( a+b \right)\left( {{a}^{2}}-ab+{{b}^{2}} \right) $ and then we will get factors for the given equation.
Complete step by step answer:
Given equation $ 8{{x}^{3}}+1 $ .
In the above equation the coefficient of $ {{x}^{3}} $ is $ 8 $ . Factorizing the number $ 8 $ .Checking whether the number $ 8 $ is divisible by $ 2 $ or not. We can say that $ 8 $ is divisible by $ 2 $ and it will give $ 4 $ as a quotient and zero reminders. Now we can write the number $ 8 $ as
$ 8=2\times 4 $
Factorizing the number $ 4 $ .
Checking whether the number $ 4 $ is divisible by $ 2 $ or not. We can say that $ 4 $ is divisible by $ 2 $
And it will give $ 2 $ as quotient and zero reminder. Now we can write the number $ 4 $ as
$ 4=2\times 2 $
From the above value we can write the number $ 8 $ as
$ \begin{align}
& 8=2\times 4 \\
& \Rightarrow 8=2\times 2\times 2 \\
\end{align} $
We know that $ a.a.a.a.a...\text{ }n\text{ times}={{a}^{n}} $ , then
$ 8={{2}^{3}} $
Substituting the above value in the given equation, then we can write
$ 8{{x}^{3}}+1={{2}^{3}}{{x}^{3}}+1 $
Applying the formula $ {{a}^{m}}{{b}^{m}}={{\left( ab \right)}^{m}} $ , then we will get
$ 8{{x}^{3}}+1={{\left( 2x \right)}^{3}}+1 $
We know that $ {{1}^{n}}=1 $ , let us assume $ n=3 $ for this problem, then $ {{1}^{3}}=1 $ . Substituting the above value in the above equation, then we will get
$ 8{{x}^{3}}+1={{\left( 2x \right)}^{3}}+{{1}^{3}} $
Applying the formula $ {{a}^{3}}+{{b}^{3}}=\left( a+b \right)\left( {{a}^{2}}-ab+{{b}^{2}} \right) $ in the above equation, then we will have
$ \begin{align}
& 8{{x}^{3}}+1=\left( 2x+1 \right)\left( {{\left( 2x \right)}^{2}}-\left( 2x \right)\left( 1 \right)+{{1}^{2}} \right) \\
& \therefore 8{{x}^{3}}+1=\left( 2x+1 \right)\left( 4{{x}^{2}}-2x+1 \right) \\
\end{align} $
Hence the factors of the given equation $ 8{{x}^{3}}+1 $ are $ 2x+1 $ , $ 4{{x}^{2}}-2x+1 $ .
Note:
In the problem, we have the constant as $ 1 $ , so we used well know formula $ {{1}^{n}}=1 $ and solved the given equation. If the constant is other than $ 1 $ then we need to factorize the constant using the same method we have used to factorize the coefficient of $ {{x}^{3}} $ . Now we will use the algebraic formula to get the factors.
Complete step by step answer:
Given equation $ 8{{x}^{3}}+1 $ .
In the above equation the coefficient of $ {{x}^{3}} $ is $ 8 $ . Factorizing the number $ 8 $ .Checking whether the number $ 8 $ is divisible by $ 2 $ or not. We can say that $ 8 $ is divisible by $ 2 $ and it will give $ 4 $ as a quotient and zero reminders. Now we can write the number $ 8 $ as
$ 8=2\times 4 $
Factorizing the number $ 4 $ .
Checking whether the number $ 4 $ is divisible by $ 2 $ or not. We can say that $ 4 $ is divisible by $ 2 $
And it will give $ 2 $ as quotient and zero reminder. Now we can write the number $ 4 $ as
$ 4=2\times 2 $
From the above value we can write the number $ 8 $ as
$ \begin{align}
& 8=2\times 4 \\
& \Rightarrow 8=2\times 2\times 2 \\
\end{align} $
We know that $ a.a.a.a.a...\text{ }n\text{ times}={{a}^{n}} $ , then
$ 8={{2}^{3}} $
Substituting the above value in the given equation, then we can write
$ 8{{x}^{3}}+1={{2}^{3}}{{x}^{3}}+1 $
Applying the formula $ {{a}^{m}}{{b}^{m}}={{\left( ab \right)}^{m}} $ , then we will get
$ 8{{x}^{3}}+1={{\left( 2x \right)}^{3}}+1 $
We know that $ {{1}^{n}}=1 $ , let us assume $ n=3 $ for this problem, then $ {{1}^{3}}=1 $ . Substituting the above value in the above equation, then we will get
$ 8{{x}^{3}}+1={{\left( 2x \right)}^{3}}+{{1}^{3}} $
Applying the formula $ {{a}^{3}}+{{b}^{3}}=\left( a+b \right)\left( {{a}^{2}}-ab+{{b}^{2}} \right) $ in the above equation, then we will have
$ \begin{align}
& 8{{x}^{3}}+1=\left( 2x+1 \right)\left( {{\left( 2x \right)}^{2}}-\left( 2x \right)\left( 1 \right)+{{1}^{2}} \right) \\
& \therefore 8{{x}^{3}}+1=\left( 2x+1 \right)\left( 4{{x}^{2}}-2x+1 \right) \\
\end{align} $
Hence the factors of the given equation $ 8{{x}^{3}}+1 $ are $ 2x+1 $ , $ 4{{x}^{2}}-2x+1 $ .
Note:
In the problem, we have the constant as $ 1 $ , so we used well know formula $ {{1}^{n}}=1 $ and solved the given equation. If the constant is other than $ 1 $ then we need to factorize the constant using the same method we have used to factorize the coefficient of $ {{x}^{3}} $ . Now we will use the algebraic formula to get the factors.
Recently Updated Pages
A boat goes 24 km upstream and 28 km downstream in class 10 maths CBSE

Write any three differences between metals and nonmetals class 10 social science CBSE

Amit standing on a horizontal plane finds a bird flying class 10 maths CBSE

Two circles of radii 5 cm and 3 cm intersect at two class 10 maths CBSE

Solve the following i John and Jivanti together have class 10 maths CBSE

What is the relation between orthocenter circumcentre class 10 maths CBSE

Trending doubts
Explain the Treaty of Vienna of 1815 class 10 social science CBSE

10 examples of evaporation in daily life with explanations

What is the full form of POSCO class 10 social science CBSE

Make a sketch of the human nerve cell What function class 10 biology CBSE

Differentiate between Xylem and phloem class 10 biology CBSE

Identify the feminine form of noun nephew a shenephew class 10 english CBSE

