(10-7y)*(7y+10) ; (x+2)^2+(2x-1)^2

(10-7y)(7y+10)=10² -7²y²= =100 - 49y (x +2)² + (2x -1)² = x² +4x +4 +4x² -4x +1 = =5x² +5 =5(x² +1)