(5а+3в)²-(5а-3в)² (a-8)(a--9)² 2(x+6)²-(20x+70) a²+(3a-2)² (5a+7в)²-70ав (5+у)²+у(у-7)

(5a+3b)²-(5a-3b)²=(25a²+30ab+9b²)-(25a²-30ab+9b²)=
=25a²+30ab+9b²-25a²+30ab-9b²=60ab

(a-8)(a-7)-(a-9)²=(a²-7a-8a+56)-(a²-18a+81)=a²-15a+56-a²+18a-81=3a-25

2(x+6)²-(20x+70)=2(x²+12x+36)-20x-70=2x²+24x+72-20x-70=2x²+4x+2

a²+(3a-2)²=a²+9a²-12a+4=10a²-12a+4

(5a+7b)²-70ab=25a²+70ab+49b²-70ab=25a²+49b²

(5+y)²+y(y-7)=25+10y+y²+y²-7y=25+3y+2y²