Question: error in using subs command

Error, invalid input: numer expects its 1st argument, x, to be of type {set, list, algebraic}, but received (2/3)*beta^2+1 = 0



i want to use the value of alpha obtained in second last line of code exi of j and use it in the last line of code i.e theta of j to obtain value of beta.

i think i am doing some mistake. i am attaching the worksheet.

Help me.

with regards.

Please Wait...