Question 171077
If {{{g(x) = x^3}}} write {{{(g(x+3)-g(x))/3}}}
 {{{g(x+3) = (x + 3)^3}}}={{{x^3+9x^3+27x+27}}}
{{{g(x+3)-g(x) = cross(x^3)+9x^2+27x+27cross(-x^3)}}}
{{{(g(x+3)-g(x))/3 = (9x^2+27x+27)/3}}}={{{3x^2+9x+9}}}