6x^7-3x^3+2x^7+8x^3=

6 x ^ 7 - 3 x ^ 3 + 2 x ^ 7 + 8 x ^ 3 =

6 x ^ 7 + 2 x ^ 7 - 3 x ^ 3 + 8 x ^ 3 =

8 x ^ 7 + 5 x ^ 3 =

x ^ 3 ( 8 x ^ 4 + 5 )