Verified answer

Объяснение:

(а²+3а)²-(1-а²)(а+1)(1-а)-5а(4а²+а)=

а⁴+6а³+9а²- (1-а²)(1+а)(1-а)-20а³-5а²;

а⁴+6а³+9а²-(1-а²)•(1-а²)-20а³-5а²;

а⁴+6а³+9а³-(1-а²)²-20а³-5а²;

а⁴+6а³+9а²-(1-2а²+а⁴)-20а³-5а²;

а⁴+6а³+9а²-1+2а²-а⁴-20а³-5а²= -14а³+6а²-1