[1] ( a + b )² = a² + 2ab + b² ,  

[2] ( a – b )² = a² – 2ab + b² ,  

[3] ( a + b ) ( a – b ) = a² – b²,  

[4] ( a + b )³ = a³ + 3a² b + 3ab² + b³ ,  

[5] ( a – b )³ = a ³ – 3a² b + 3ab² – b³ ,  

[6] ( a + b )( a² – ab + b² ) = a³ + b³ ,  

[7] ( a – b )( a ² + ab + b² ) = a³ – b³ .  

РЕШЕНИЕ:  

1) (а-3)*(а+3)  

2) (х+5)*(x+5)  

3) (a+4)*(a^2-4a+16)  

4) (b-1)*(b^2+b+1)  

5) (y-1)*(y-1)