Question

(12а-1)² - 1=
(а² - 3а) =
5(3а+7)² =
(5а - 3с)(5а + 3с) - (7с - а)(7с + а) =

Answer 1

1) (12а-1)²-1=144а²-24а+1-1=144а²-24а=24а(6а-1)
2) (а²-3а)=а(а-3)
3) 5(3а+7)²=(15а+35)²=225а²+1225=25(9а²+49)
4) (5а-3с)(5а+3с)-(7с-а)(7с+а)=25а²-9с²-(49с²-а²)=25а²-9с²-49с²+а²=26а²-58с²