Question

if x-1/3 =3 . find x³-1/x³

Answer 1

x=10/3
(10/3)^3-(3/10)^3
=1000/27-27/1000
=[(1000)^2-(27)^2]/27000
=(1000000-243)/27000
=999757/27000
=37.03

Answer 2

given :-

x - 1/3 = 3

therefore x = 3/1 + 1/3

lcm of 3 and 1 = 1 × 3 = 3

==> x = (3×3)/(1×3) + (1×1)/(3×1)

==> x = 9/3 + 1/3

==> x = 10/3

so x³ = (10/3)³ = (10×10×10)/(3×3×3)

= 1000/27

==> 1/x³ = 1/1 × 27/1000

==> 1/x³ = 27/1000

hence, final answer = x³ - 1/x³

= 1000/27 - 27/1000

= (1000×1000)/(27×1000) - (27×27)/(1000×27)

= 1000000/27000 - 729/27000

= 999271/27000

HOPE THIS HELPS..!!