1) x^2 + 6x + 9 = ( x + 3)^2
2) 25x^2 - 10xy + y^2 = ( 5x - y)^2
1) ( a^2 + b^3)^2 = a^4 + 2a^2b^3 + b^6
2) (2y + 1/4)^2 = 4y^2 + y + 1/16
3) ( - 7x - 1)^2 = 49x^2 + 14x + 1
1) y^5 - 25y^3 = y^3(y^2 - 25)= y^3( y - 5)(y + 5)
2) 16x + 8x^2 + x^3 =x^3 + 8x^2 + 16x= x(x^2 + 8x + 16)=
= x( x + 4)^2 = x( x + 4)(x + 4)