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