Question 1083283
Start by writing 2+i in polar form, because in that form the ^7 part is easier to handle:

{{{ (2+i) = sqrt(2^2+1^2)e^(i*tan^-1(1/2)) }}} = {{{ sqrt(5)*e^(i*26.5651^o) }}}


{{{ (sqrt(5)*e^(i*26.5651^o) )^7 =  (sqrt(5))^7*e^(7*i*(26.5651^o)) }}}
= {{{ 5^(7/2) * e^(i*185.9557^o) }}}    <<< 5^(7/2) * e^(i*185.9557) 
= {{{ 279.50850*e^(i*185.9557^o) }}}
= {{{ 279.50850*(cos(185.9557) + i*sin(185.9557)) }}}
= {{{ 279.50850*(-0.99469 + i*(-0.1037595)) }}}
= {{{  highlight(-278.02431 - i*29.00166) }}}