[_Liouville, [_2nd_order, _with_linear_symmetries], [_2nd_order, _reducible, _mu_x_y1], [_2nd_order, _reducible, _mu_xy]]
Book solution method
TO DO
Mathematica ✓
cpu = 0.214429 (sec), leaf count = 63
Maple ✓
cpu = 0.087 (sec), leaf count = 52
DSolve[Sqrt[a^2 + x^2]*(b*y'[x]^2 + y[x]*y''[x]) == y[x]*y'[x],y[x],x]
Mathematica raw output
{{y[x] -> C[2]*((1 + b)*x^2 + (1 + b)*x*Sqrt[a^2 + x^2] + 2*C[1] + a^2*(1 + b)*L
og[x + Sqrt[a^2 + x^2]])^(1 + b)^(-1)}}
Maple raw input
dsolve((a^2+x^2)^(1/2)*(y(x)*diff(diff(y(x),x),x)+b*diff(y(x),x)^2) = y(x)*diff(y(x),x), y(x),'implicit')
Maple raw output
y(x)/(b+1)*y(x)^b-1/2*(a^2*ln(x+(a^2+x^2)^(1/2))+x*(x+(a^2+x^2)^(1/2)))*_C1-_C2
= 0