Respuesta :

OK....
Your answer would be  
[tex]9x^5-42x^3[/tex]
H0P3 It H3LPS :)
The first thing you need to do is distribute the 7x^2 to the values inside the parenthesis. 

7x^2(x^3-6x)+2x^5
7x^5-42x^3+2x^5 combine like terms
9x^5-42^3