We have, ‌x=−5+2√−4 ‌x+5=4i On squaring both sides, ‌x2+10x+25=−16 ⇒‌‌x2+10x=−41 or x2+10x+41=0 Now, ‌x4+9x3+35x2−x+4 =‌x4+10x3+41x2−x3−6x2−x+4 =‌x2(x2+10x+41)−x3−10x2−41x ‌+4x2+40x+4 Now, ‌x4+9x3+35x2−x+4 =‌x4+10x3+41x2−x3−6x2−x+4