Question 1149771
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<pre>

    3x^4 - 2x^2 = 16.


Introduce new variable t = x^2.

Then your equation takes the form


    3t^2 - 2t - 16 = 0.


Solve it using the quadratic formula


    {{{t[1,2]}}} = {{{(2 +- sqrt(2^2 + 4*3*16))/(2*3)}}} = {{{(2 +- sqrt(196))/6}}} = {{{(2 +- 14)/6}}}.


Only positive root is acceptable (since  t = x^2),  t = {{{(2 + 14)/6}}} = {{{16/6}}} = {{{8/3}}}.


It implies  x^2 = {{{8/3}}};  hence,  x = +/- {{{sqrt(8/3)}}} = +/- {{{(2*sqrt(6))/3}}}.    <U>ANSWER</U>
</pre>

Solved.


Introducing new variable is the <U>STANDARD WAY</U> solving such problems.