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

Question

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

Video Solution

Solution Steps

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 Solution

The equation in the problem is:

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

First, let's note that in the left side we can factor the expression using a common factor, the largest common factor for the numbers and variables in this case is 7x9 7x^9 since 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

Let's continue and address the fact that on the left side of the equation 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 get a result of 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:

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 extracted 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.

Answer

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