Solve the Polynomial Equation: 7x^10 - 14x^9 = 0

Polynomial Factoring with Common Factors

Solve the following equation:

7x1014x9=0 7x^{10}-14x^9=0

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Find X
00:03 Factor with the term X in the ninth power
00:14 Factor 14 into factors 7 and 2
00:17 Take out the common factor from parentheses
00:34 This is one solution that makes the equation zero
00:46 Now let's check which solutions zero out the second factor
00:53 And this is the solution to the question

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following equation:

7x1014x9=0 7x^{10}-14x^9=0

2

Step-by-step solution

Shown below is the given equation:

7x1014x9=0 7x^{10}-14x^9=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 variables in this case is 7x9 7x^9 given that the ninth power is the lowest power in the equation and therefore is included in both the term with the tenth power and the term with the ninth power. Any power higher than this is not included in the term with the ninth power, which is the lowest, and therefore this is the term with the highest power that can be factored out as a common factor from all terms for the variables,

For the numbers, note that 14 is a multiple of 7, therefore 7 is the largest common factor for the numbers in both terms of the expression,

Let's continue and perform the factoring:

7x1014x9=07x9(x2)=0 7x^{10}-14x^9=0 \\ \downarrow\\ 7x^9(x-2)=0

On 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, since the only way to obtain a result of 0 from a multiplication operation is to multiply by 0, at least one of the expressions in the multiplication on the left side must equal zero,

Meaning:

7x9=0/:7x9=0/9x=0 7x^9=0 \hspace{8pt}\text{/}:7\\ x^9=0 \hspace{8pt}\text{/}\sqrt[9]{\hspace{6pt}}\\ \boxed{x=0}

In solving the equation above, we first divided both sides of the equation by the term with the variable, and then we proceeded to extract a ninth root from both sides of the equation.

(In this case, extracting an odd root from the right side of the equation yielded one possibility)

Or:

x2=0x=2 x-2=0 \\ \boxed{x=2}

Let's summarize the solution of the equation:

7x1014x9=07x9(x2)=07x9=0x=0x2=0x=2x=0,2 7x^{10}-14x^9=0 \\ \downarrow\\ 7x^9(x-2)=0\\ \downarrow\\ 7x^9=0 \rightarrow\boxed{ x=0}\\ x-2=0\rightarrow \boxed{x=2}\\ \downarrow\\ \boxed{x=0,2}

Therefore, the correct answer is answer A.

3

Final Answer

x=2,x=0 x=2,x=0

Key Points to Remember

Essential concepts to master this topic
  • Factoring Rule: Extract the greatest common factor from all terms first
  • Technique: Factor out 7x9 7x^9 to get 7x9(x2)=0 7x^9(x-2)=0
  • Check: Substitute x=0 and x=2: both make the original equation equal zero ✓

Common Mistakes

Avoid these frequent errors
  • Trying to solve without factoring first
    Don't attempt to solve 7x1014x9=0 7x^{10}-14x^9=0 directly by moving terms = you'll miss solutions! High-degree equations are nearly impossible to solve this way. Always factor out the greatest common factor first, then use the zero product property.

Practice Quiz

Test your knowledge with interactive questions

Solve the following equation:


\( 2x^2-8=x^2+4 \)

FAQ

Everything you need to know about this question

How do I find the greatest common factor with variables?

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Look for the smallest exponent among all terms. Here, both terms have x, but the powers are 10 and 9, so x9 x^9 is the highest power that divides both terms.

Why does 7x^9 = 0 give me x = 0?

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When you have 7x9=0 7x^9 = 0 , divide both sides by 7 to get x9=0 x^9 = 0 . The only number that when raised to any positive power equals zero is zero itself!

What is the zero product property?

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If A×B=0 A \times B = 0 , then either A = 0 or B = 0 (or both). This is why 7x9(x2)=0 7x^9(x-2) = 0 means either 7x9=0 7x^9 = 0 or x2=0 x-2 = 0 .

Can I have more than two solutions?

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Yes! The maximum number of solutions for a polynomial equation equals its highest degree. Since this is degree 10, it could have up to 10 solutions, but here we only get 2 distinct ones.

Why isn't x = 0 counted multiple times?

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Even though x9=0 x^9 = 0 technically gives us x = 0 nine times (called multiplicity 9), we only list each distinct solution once in our final answer.

How do I check my answers?

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Substitute each solution back into the original equation: For x = 0: 7(0)1014(0)9=00=0 7(0)^{10} - 14(0)^9 = 0 - 0 = 0 ✓ For x = 2: 7(2)1014(2)9=7(1024)14(512)=71687168=0 7(2)^{10} - 14(2)^9 = 7(1024) - 14(512) = 7168 - 7168 = 0 ✓

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