Question: given the lemniscate of bernoulli (x^2 + y^2)^2 = (25/3) (x^2 -y^2) does the curve have any horizontal tangent line?

Question:given the lemniscate of bernoulli (x^2 + y^2)^2 = (25/3) (x^2 -y^2)

does the curve have any horizontal tangent line?

I am trying to solve questions out of textbook and I do not understand. please help and explain if work is not clear. Thank you