Question

$$x = 3 ^ { \frac { 1 } { 3 } } + 3 ^ { - \frac { 1 } { 3 } } , : 3 x ^ { 3 } - 9 x = 6$$

Answer

$$x=(3^13+1/3^13)/f,0,sqrt((f/3+3)/(s*h^2*o*w*t^2*a)),-sqrt((f/3+3)/(s*h^2*o*w*t^2*a))$$

Solution


Use Negative Power Rule: \({x}^{-a}=\frac{1}{{x}^{a}}\).
\[\begin{aligned}&1\times fx={3}^{13}+\frac{1}{{3}^{13}}\\&showthat\times 3{x}^{3}-9x=10\end{aligned}\]
Simplify  \(1\times fx\)  to  \(fx\).
\[\begin{aligned}&fx={3}^{13}+\frac{1}{{3}^{13}}\\&showthat\times 3{x}^{3}-9x=10\end{aligned}\]
Use Product Rule: \({x}^{a}{x}^{b}={x}^{a+b}\).
\[\begin{aligned}&fx={3}^{13}+\frac{1}{{3}^{13}}\\&s{h}^{2}ow{t}^{2}a\times 3{x}^{3}-9x=10\end{aligned}\]
Regroup terms.
\[\begin{aligned}&fx={3}^{13}+\frac{1}{{3}^{13}}\\&3s{h}^{2}ow{t}^{2}a{x}^{3}-9x=10\end{aligned}\]
Break down the problem into these 2 equations.
\[fx={3}^{13}+\frac{1}{{3}^{13}}\]
\[fx=3s{h}^{2}ow{t}^{2}a{x}^{3}-9x\]
Solve the 1st equation: \(fx={3}^{13}+\frac{1}{{3}^{13}}\).
\[x=\frac{{3}^{13}+\frac{1}{{3}^{13}}}{f}\]
Solve the 2nd equation: \(fx=3s{h}^{2}ow{t}^{2}a{x}^{3}-9x\).
\[x=0,\pm \sqrt{\frac{\frac{f}{3}+3}{s{h}^{2}ow{t}^{2}a}}\]
Collect all solutions.
\[x=\frac{{3}^{13}+\frac{1}{{3}^{13}}}{f},0,\pm \sqrt{\frac{\frac{f}{3}+3}{s{h}^{2}ow{t}^{2}a}}\]