2x8+4x7-6x6+4x5=2x5(x3+2x2-3x+2).
Note that if the original expression had been -2x8+4x7-6x6+4x5, the cubic in parentheses would have factorised further:
2x5(-x3+2x2-3x+2)=-2x5(x-1)(x2-x+2). The cubic doesn't otherwise factor rationally.
Note that if the original expression had been 2x8+4x7+6x6+4x5, the cubic in parentheses would have factorised further:
2x5(x3+2x2+3x+2)=2x5(x+1)(x2+x+2). The cubic doesn't otherwise factor rationally.