Question 710031
{{{ A=( matrix(3,3,3,0,0,0,3,0,0,0,3) ) = 3( matrix(3,3,1,0,0,0,1,0,0,0,1) ) = 3I }}}


So, {{{ A^4 = (3I)^4 = (3^4)I =81I = ( matrix(3,3,81,0,0,0,81,0,0,0,81) ) }}}