раскройте скобки (2t+1)^2
(K^2-5y)^2
(7c+3)(7c-3)

1) 4t^2 + 4t +12) k^4 -10k^2y+25y^23) 49c^2 - 9

= 4t^2 + 4t + 1---------------------------= k^4 - 10k^2y + 25y^2----------------------------= 49c^2 - 9