Question

if x2 +1/x2=83 find the value of x3-1/x3

Answer 1

x^2+1/x^2=83

(x-1/x)^2=83-2

x-1/x=9

(x-1/x)^3=x^3-3x+3/x-1/x^3

729+3x-1/x=x^3-1/x^3

x^3-1/x^3=729+3 (x-1/x)

=729-27

=702

so your answer is 702

Answer 2

(a-b)^3=a^3-b^3-3ab (a-b)