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

Question

How many solutions does the equation have?

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

Video Solution

Solution Steps

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 Solution

Let's solve the given equation:

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

First, we identify that we can factor the expression on the left side using factoring out the common factor:

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

We'll continue and factor the expression in parentheses, we can identify that it can be factored using the perfect square trinomial formula:

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

Let's do it:

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 this factoring using the mentioned formula was possible only because the middle term in the expression (which is in first power in this case and highlighted in blue in the previous calculation) indeed matched the middle term in the perfect square trinomial formula,

We'll continue and get two simpler equations and 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} L

et's summarize the equation solving steps:

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.

Answer

Two solutions