\[ a+\left (x^2-1\right ) y'(x)-x y(x)=0 \] ✓ Mathematica : cpu = 0.0236248 (sec), leaf count = 21
\[\left \{\left \{y(x)\to a x+c_1 \sqrt {x^2-1}\right \}\right \}\] ✓ Maple : cpu = 0.021 (sec), leaf count = 20
\[y \relax (x ) = \sqrt {x -1}\, \sqrt {1+x}\, c_{1}+a x\]