To rationalize the denominator of the expression will be as follows;
-49/[(7-2i)-(4+9i)
=-49/[7-4-2i+9i]
=-49/[3+7i]
to rationalize the denominator we multiply both the numerator and the denominator by [3-7i]
hence;
-49/[3+7i]*[3-7i]/[3-7i]
=[-49(3-7i]/(9+49]
=(-147+343i)/58
The answer is (-147+343i)/58
