a2+1/a2 = 51 হলে, a−1/a এর মান কত?

a²+1/a² = 51 হলে, a−1/a এর মান কত?

A ±3

B ±5

C ±7

D ±9

Solution

Correct Answer: Option C

a²+1/a² = 51

=>(a - 1/a)^2 + 2a. 1/a = 51

=> (a - 1/a)^2 = 51 - 2

=> (a - 1/a)^2 = 49

=> a - 1/a = ±7