Question 32915
{{{(-2*a^4)^3 * (3*a^(-5))^2}}} = 
{{{(-2*a^4)*(-2*a^4)*(-2*a^4)*(3*a^(-5))*(3*a^(-5))}}} =
{{{(-8 * a^(4+4+4)) * (9 * a^(-5-5))}}} =
{{{(-8 * a^12) * (9 * a^(-10))}}} =
{{{-72 * a^2}}}
..................
{{{ 3 * a^2 - 15 * a^2 - 42}}} =
first factor out {{{a^2}}} =
{{{a^2 * (3 - 15) -42}}} =
{{{-12 * a^2 -42}}} =
factor out -6
{{{-6 * (2 * a^2 + 7)}}}