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Mathematics 7 Online
OpenStudy (anonymous):

how many answers does this equation have?

OpenStudy (anonymous):

\[\sqrt[3]{x^2-3x}-2\sqrt[3]{(x^2-3x)^2}+1=0\]

OpenStudy (mathmate):

I would start with a substitution and solve the quadratic.

OpenStudy (thomas5267):

mathmate is essentially saying the you should rewrite the equation in terms of \(u=\sqrt[3]{x^2-3x}\).

OpenStudy (anonymous):

\[u-u^2+1=0\] u=\[\frac{ 1\pm \sqrt{5} }{ 2 }\]

OpenStudy (anonymous):

\(\large \Rightarrow \\\large \sqrt[3]{x^2-3x}=\frac{1+\sqrt{5}}{2}\\\large x^2-3x-\frac{(1+\sqrt{5})^3}{8}=0\) This equation has 2 solutions And \(\large \sqrt[3]{x^2-3x}=\frac{1-\sqrt{5}}{2}\\\large x^2-3x-\frac{(1-\sqrt{5})^3}{8}=0\) This equation has 2 solution too Thus, the equation \(\large \sqrt[3]{x^2-3x}-2\sqrt[3]{(x^2-3x)^2}+1=0\) has 4 solution

OpenStudy (mathmate):

Sorry guys, unless I'm mistaken, isn't the original equation \((x^2-3x)^{1/3}-2(x^2-3x)^{2/3}+1=0\) or \(u-2u^2+1=0\) That would change a few numbers, but I see that the method does not really change.

OpenStudy (mathmate):

I get u=1 or u=\(\large-\frac{1}{2}\).

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