-25i25
(-25i)^25= -8.881784..... X 10^34i
\(-25i^{25}\\=-25*i^{24}*i\\=-25*(i^{2})^{12}*i\\=-25*(-1)^{12}*i\\ =-25*((-1)^{2})^6*i\\ =-25*(1)^6*i\\ =-25*1*i\\ =-25i\)