Use Cramer's rule to compute the solutions of the system:
{5x₁ + 2sx₂ = -1 3x₁ + 6sx₂ = 4 }
determine the values of the parameter s for which the system has a unique solution.
a) s ≠ -¹⁄₂
b) s = -¹⁄₂
c) s = ¹⁄₂
d) s = -1