Solve x³-2x²+x=0: Finding All Solutions of a Cubic Equation

Cubic Factorization with Perfect Square Trinomials

Determine how many possible solutions there are for the following equation:

x32x2+x=0 x^3-2x^2+x=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 out common X
00:30 Decompose using trinomial
00:35 Find what zeroes each factor
00:39 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

Determine how many possible solutions there are for the following equation:

x32x2+x=0 x^3-2x^2+x=0

2

Step-by-step solution

Let's solve the given equation:

x32x2+x=0 x^3-2x^2+x=0

Note that we can factor the expression on the left side by factoring out the common factor:

x32x2+x=0x(x22x+1)=0 x^3-2x^2+x=0 \\ \downarrow\\ x(x^2-2x+1)=0

Proceed to factor the expression inside of the parentheses. It can be factored by using the perfect square trinomial formula:

(a±b)2=a2±2ab+b2 (a\pm b)^2=a^2\pm2ab+b^2

As shown below:

x(x22x+1)=0x(x22x+12)=0x(x22x1+12)=0x(x1)2=0 x(x^2-2x+1)=0 \\ x(x^2 \textcolor{blue}{-2x}+1^2)=0 \\ x(x^2\textcolor{blue}{-2\cdot x \cdot 1}+1^2)=0 \\ \downarrow\\ x(x-1)^2=0

We should emphasize that the process of factoring by using the mentioned formula was only possible due to the middle term in the expression. (The first power in this case is highlighted in blue indeed matched the middle term in the perfect square trinomial formula)

Having obtained two simpler equations let's proceed to solve them:

x(x1)2=0x=0(x1)2=0/x1=0x=1x=0,1 x(x-1)^2=0 \\ \boxed{x=0}\\ (x-1)^2=0\hspace{6pt}\text{/}\sqrt{\hspace{4pt}}\rightarrow x-1=0\rightarrow \boxed{x=1}\\ \downarrow\\ \boxed{x=0,1}

Shown below is a summary of the various steps to solve the given equation:

x32x2+x=0x(x22x+1)=0x(x1)2=0x=0(x1)2=0x=1x=0,1 x^3-2x^2+x=0 \\ \downarrow\\ x(x^2-2x+1)=0 \\ \downarrow\\ x(x-1)^2=0 \\ \downarrow\\ \boxed{x=0}\\ (x-1)^2=0\rightarrow \boxed{x=1}\\ \downarrow\\ \boxed{x=0,1}

Therefore, the given equation has two different solutions,

Which means - the correct answer is answer B.

3

Final Answer

Two solutions

Key Points to Remember

Essential concepts to master this topic
  • Factoring Strategy: Factor out common term x first to simplify cubic equation
  • Perfect Square: Recognize x22x+1=(x1)2 x^2-2x+1 = (x-1)^2 pattern
  • Solution Check: Verify x=0 and x=1 by substituting back into original equation ✓

Common Mistakes

Avoid these frequent errors
  • Counting repeated roots as multiple solutions
    Don't count x=1 twice just because (x-1)² appears = claiming three solutions! The squared factor means x=1 is a repeated root, not two separate solutions. Always count distinct values only.

Practice Quiz

Test your knowledge with interactive questions

\( x^2+6x+9=0 \)

What is the value of X?

FAQ

Everything you need to know about this question

Why does this cubic equation only have 2 solutions instead of 3?

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Great question! While cubic equations can have up to 3 solutions, this one has a repeated root. The factor (x1)2 (x-1)^2 means x=1 is a solution twice, but we only count distinct values.

How do I recognize a perfect square trinomial?

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Look for the pattern a2±2ab+b2 a^2 ± 2ab + b^2 . In x22x+1 x^2-2x+1 : first term is x2 x^2 , last term is 12 1^2 , and middle term is 2(x)(1) -2(x)(1) . Perfect match!

What if I can't factor out x first?

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Always check for common factors first! If every term contains the same variable or number, factor it out. This makes the remaining polynomial much easier to work with.

Could this equation have complex solutions too?

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In this case, no! We found all real solutions: x=0 and x=1. Since we completely factored the polynomial as x(x1)2 x(x-1)^2 , these are the only solutions.

How do I know when I've found all solutions?

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Count the degree of your polynomial. A cubic (degree 3) has at most 3 solutions. Here we have x=0 (once) and x=1 (twice), accounting for all 3 roots with 2 distinct values.

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