Question

if xsquare +i upon xsquare =18 find the value of x cube -1 upon xcube

Answer 1

substract 2 in both sides ;x^2+1/x^2-2=18-2; (x-1/x)^2=16;x-1/x=✔16=4;again cubes with both sides; x^3-1/x^3-3 (x-1/x)=64;x^3-1/x^3=64+12=76