When I solved the simultaneous equations, the result was derived as "{ }". The input is as follows.
s /. Out[112] θ /. Out[113] {(-((36*a*θ)/(-36 + 9*b^2 + 2*θ^2)^2) + (18*a* b*θ)/(-36 + 9*b^2 + 2*θ^2)^2 + (2* a*(-2 + b)*θ)/(-72 + 18*b^2 + 4*θ^2) - (4*a*(-2 + b)*θ)/(36*(-4 + b^2) + 8*θ^2) - (18*(-2 + b)*θ* Subscript[c, f])/(-36 + 9*b^2 + 2*θ^2)^2 - (2*(-2 + b)*θ* Subscript[c, f])/(-72 + 18*b^2 + 4*θ^2) + (4*θ*((-2 + b)*Subscript[c, f] - 2*Subscript[c, h]))/(36*(-4 + b^2) + 8*θ^2) + (36*θ* Subscript[c, h])/(-36 + 9*b^2 + 2*θ^2)^2 + (4*θ*Subscript[c, h])/(-72 + 18*b^2 + 4*θ^2))/((18*θ^2)/(-36 + 9*b^2 + 2*θ^2)^2 - (18*(-2 + b)*(2 + b))/(-72 + 18*b^2 + 4*θ^2) + (18*(-2 + b)*(2 + b))/(36*(-4 + b^2) + 8*θ^2))} Out[115] Rs = Out[114] Rθ = Out[115] {(-((36*a*θ)/(-36 + 9*b^2 + 2*θ^2)^2) + (18*a* b*θ)/(-36 + 9*b^2 + 2*θ^2)^2 + (2* a*(-2 + b)*θ)/(-72 + 18*b^2 + 4*θ^2) - (4*a*(-2 + b)*θ)/(36*(-4 + b^2) + 8*θ^2) - (18*(-2 + b)*θ* Subscript[c, f])/(-36 + 9*b^2 + 2*θ^2)^2 - (2*(-2 + b)*θ* Subscript[c, f])/(-72 + 18*b^2 + 4*θ^2) + (4*θ*((-2 + b)*Subscript[c, f] - 2*Subscript[c, h]))/(36*(-4 + b^2) + 8*θ^2) + (36*θ* Subscript[c, h])/(-36 + 9*b^2 + 2*θ^2)^2 + (4*θ*Subscript[c, h])/(-72 + 18*b^2 + 4*θ^2))/((18*θ^2)/(-36 + 9*b^2 + 2*θ^2)^2 - (18*(-2 + b)*(2 + b))/(-72 + 18*b^2 + 4*θ^2) + (18*(-2 + b)*(2 + b))/(36*(-4 + b^2) + 8*θ^2))} Out[117] Solve[{s - Rs == 0, θ - Rθ == 0}, {s, θ}] {}
If a symbol such as "{ }" appears in the output, what does this mean? When the equation is wrong or the calculation is wrong, does a symbol like "{ }" appear in the output?