∣∣ ∣ ∣ ∣∣abcdaa+ba+b+ca+b+c+da2a+b3a+2b+c4a+3b+2c+da3a+b6a+3b+c10a+6b+3c+d∣∣ ∣ ∣ ∣∣
=∣∣ ∣ ∣ ∣∣abcd0aa+ba+b+c0a2a+b3a+2b+c0a3a+b6a+3b+c∣∣ ∣ ∣ ∣∣[R4→R4−R3;R3→R3−R2;R2→R2−R1]
=a∣∣ ∣∣aa+ba+b+ca2a+b3a+2b+ca3a+b6a+3b+c∣∣ ∣∣
=a∣∣ ∣∣aa+ba+b+c0a2a+b0a3a+b∣∣ ∣∣[R3→R3−R2;R2→R2−R1]
=a2∣∣∣a2a+ba3a+b∣∣∣
=a2(3a2+ab−2a2−ab)=a4