Consider first two equations : 2x + 3y = –4 and 3x + 4y = –6 We have Δ = ​23​34​​ = - 1 ≠0 Δx​ = ​−4−6​34​​ = 2 and Δy​ = ​23​−4−6​​ = 0 ∴ x = –2 and y = 0 Now this solution satisfies the third, so the equations are consistent with unique solution.