Explanation:
40 x^3 + 36x^5 can factor 4 out of 40 and 36 to get
4 ( 10x^3 + 9x^5 ) now, you can factor out x^3 to get
4x^3 ( 10 + 9x^2 ) I think the 10 + 9x^2 is the greater of the two factors
but your question may be looking for 4x^3 as the greatest common factor of the original two terms .....