1/a = 3-a হলে a³+1/a³ = কত?

1/a = 3-a হলে a³+1/a³ = কত?

A 17

B 18

C 19

D 20

Solution

Correct Answer: Option B

1/a = 3-a

a+1/a = 3

এখন, a^3+ 1/a^3 = (a+1/a)^3 - 3.a.1/a(a+1/a)

= (3)^3 - 3.3 = 27 - 9

a^3+1/a^3 = 18