Question 1041798
{{{A = int((kx-x^2), dx, 0,k) = 6}}}

==> {{{((k/2)x^2 - x^3/3)0^k = 6}}}

==> {{{k^3/2 - k^3/3 = k^3/6 = 6}}}  ==> {{{k^3 = 36}}}

Therefore, {{{k = root(3,36)}}}.