4)
a) = 16x² + 4x + 1
b) = 9x² - 30x + 25
c) = x² + 10x + 25
5)
a) = 7x² (x² - 1) - 9x² (x - 1) = (x - 1)(7x²-9x²) = (x-1)(√7x+3x)(√7x-3x)
b) = x²(x² - x) - x² - x = (x² - x)(x² - 1) = (x² - x)(x-1)(x+1)
c) = x²(x-5) + 4(x - 5) = (x - 5)(x²+4)
6)
a) = (5x - 1)²
b) = (0,5x +1)²
c) = (x - 2)³
d) (x + 1)³
