1) (9a-3b+c)(9a+3b-c); 2) (m+3-5n)(m+3+5n)
Объяснение:
1) = 81a²-(9b²-6bc+c²)=81a²-(3b-c)²=(9a-3b+c)(9a+3b-c)
2) = (m²+6m+9)-25n²= (m+3)²-25n²= (m+3-5n)(m+3+5n)
