1) 25a²-(a+3)²=25a²-a²-6a-9=24a²-6a-9=3(8a²-2a-3)
8a²-2a-3=0
a1,2=1/16 * (2 +- √(9+4*8*2))=1/16 * (2 +- √73)
3(8a²-2a-3) = 24(a - 1/16 * (2 - √73))(a - 1/16 * (2 + √73))
2) 3a²x² - 6a³x + 12a²
= 3a²x(x - 2a + 4x²)
4x²+x-2a=0
x1,2=1/8 * (-1 +- √(32a+1))
3a²x(x - 2a + 4x²) = 12a²x(x+1+√(32a+1))(x+1-√(32a+1))