Using properties of determinants, prove that: ∣∣ ∣∣x+yxx5x+4y4x2x10x+8y8x3x∣∣ ∣∣=x3
LHS: Let Δ=∣∣ ∣∣x+yxx5x+4y4x2x10x+8y8x3x∣∣ ∣∣ [Applying R1→R2−4R1 and R3→R3−8R1
=∣∣ ∣∣x+yxxx0−2x2x0−5x∣∣ ∣∣ [Expanding along C2]
=−x[x(−5x)−(2x)(−2x)]=−x[−5x2+4x2]
=x3=RHS.