[tex]\bf 30x^7+8x^2~~ \begin{cases} 30=&\boxed{2}\cdot 3\cdot 5\\ 8=&\boxed{2}\cdot 2\cdot 2\\ x^7=&x^{2+5}\\ &\boxed{x^2} x^5\\ x^2=&\boxed{x^2} \end{cases}\implies \stackrel{GCF}{(2)(x^2)\implies 2x^2} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ 30x^7+8x^2\implies 2x^2(15x^5+4)[/tex]