-3x^2+10x-3
This is of the form ax^2+bx+c. We need to find two values, j and k, such that:
jk=ac=9 and j+k=b=10, so j and k must be 1 and 9.
Now replace bx with jx and kx in the original equation...
-3x^2+x+9x-3 now factor 1st and 2nd pair of terms
-x(3x-1)+3(3x-1)
(-x+3)(3x-1) or equivalently...
-(x-3)(3x-1) or as they put it:
-(3x-1)(x-3)
