What is y in the equation 3y4-y2?

3y^(4)- y^(2) = 0

Factor

y^(2) [ 3y^(2) - 1] = 0

Hence

y^(2) = 0

It follows that y = 0

And

3y^(2) - 1 = 0

y^(2) = 1/3

y = +/- sqrt( 1/3) = +/-0.577350269.....

Hence y = 0 or y = +/-0.577350269.... to make the eq'n equal to zero.