Positive real numbers x,y satisfy the equations x^2 + y^2 = 1 and x^4 + y^4= 5/8 . Find xy.
\((x^2 + y^2)^2 = x^4 + 2(xy)^2 + y^2\\\\ 1 = \frac{5}{8}+2(xy)^2\)
Can you take it from here?
