1) (5a+7b) ²-70ab 2) (x-8) ²-2x (6-x) ² 3) -6 (2x-y) ² 4) (5+y) ²+y

(5a+7b) ²-70ab=25a²+70ab+49b²-70ab=25a²+49b² (x-8) ²-2x (6-x) ²=x²-16x+64-2x (36-12x+x²)=x²-16x+64-72x+24x²-2x3=2x3+25x²-8x+64-6 (2x-y) ²=-6 (4x²-4xy+y²)=-24x²+24xy-6y² (5+y) ²+y (y-7)=25+10y+y²+y²-7y=2y²+3y+25 9b²- (a-3b) ²=9b²-a²-6ba+9b²=18b²-a²-6ba