What is the interval of validity for the solution y=−1/xy = -1/xy=−1/x of y′=y2y' = y^2y′=y2 with y(1)=−1y(1) = -1y(1)=−1?
(0,∞)(0, \infty)(0,∞)
(−∞,0)(-\infty, 0)(−∞,0)
(−1,1)(-1, 1)(−1,1)
[1,∞)[1, \infty)[1,∞)