How do you factor these? The split middle term doesn't work.

Q1:

-6a^2 - 5a -1

product = 6, sum = -5

-6a^2 + a - 6a -1

(-6a^2 + a) - (6a + 1)

a(-6a + 1) - (6a + 1)

(-6a + 1) (a - 1) -> this is not giving me the same answer if foil

Q2:

25a^2 -10a + 1

product = 25, sum = -10

?? -> cannot find 2 numbers whose product is 25 and difference is -10

Q3:

12x^2 +17xy + 6y^2

?? -> Two terms with ^2, how do you do this?

Q4:

-30x^3 + 2x^2 + 12x

?? -> One term with ^3 and another with ^2, how do you do this?

Please help.

Thanks.