Factor
9. 6a^4-11a^2-10
10. 2x^2(x-1)+3x(x-1)-2(x-1)
aside from trial and error, or experience, you can always use the quadratic formula to find the factors. For example, #9 is not obvious, but you know that
a = (11±√361)/12 = (11±19)/12 = 5/2 or -2/3
6a^4-11a^2-10 = (2x-5)(3x+2)
#10 is a bit easier. (x-1)(2x^2+3x-2)
I'm sure you can factor that, since 3 = 2*2 - 1