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а) 4x^2 y^2-9a^4=

б) 25a^2 - (a+3) ^2=

в) 27m^3+n^3

1) 4x²y²-9aˇ4 = (2xy) ² - (3a²) ² = (2xy+3a²) (2xy-3a²)

2) 25a² - (a+3) ² = (5a) ² - (a+3) ² = (5a+a+3) (5a-a-3) = (6a+3) (4a-3) = 3 (2a+1) (4a-3)

3) 27m³+n³ = (3m) ³+n³ = (3m+n) (9m²-3mn+n²)