Solve the Equation: 8x - x⁴ = 0 | Fourth-Degree Polynomial

Question

Solve the following problem:

8xx4=0 8x-x^4=0

Video Solution

Solution Steps

00:00 Find X
00:03 Factor with term X
00:08 Take out the common factor from parentheses
00:18 This is one solution that zeros the equation
00:23 Now let's check which solutions zero the second term
00:26 Isolate X and extract the cube root
00:42 Break down 8 to 2 cubed
00:46 And this is the solution to the problem

Step-by-Step Solution

Shown below is the given equation:

8xx4=0 8x-x^4=0

Note that on the left side we are able to factor the expression by using a common factor. The largest common factor for the numbers and variables in this case is x x 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 fourth 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:

8xx4=0x(8x3)=0 8x-x^4=0 \\ \downarrow\\ x(8-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:

x=0 \boxed{x=0}

or:

8x3=08=x3/3x=2 8-x^3=0\\ 8=x^3\hspace{8pt}\text{/}\sqrt[3]{\hspace{6pt}}\\ \downarrow\\ \boxed{x=2} (in this case taking the odd root of the left side of the equation will yield only one possibility)

Let's summarize the solution of the equation:

8xx4=0x(8x3)=0x=08x3=0x=2x=0,2 8x-x^4=0 \\ \downarrow\\ x(8-x^3)=0 \\ \downarrow\\ \boxed{ x=0}\\ 8-x^3=0 \rightarrow \boxed{x=2}\\ \downarrow\\ \boxed{x=0,2}

Therefore the correct answer is answer A.

Answer

x=0,2 x=0,2