Question

Class - 8

(solve the question.)​

Answer 1

Answer:

115√21.

Step-by-step explanation:

x + 1/x = 5

x² + 1/x² = (x + 1/x)² - 2 = 25 - 2 = 23.

(x -1/x)² = (x + 1/x)² - 4 = 25 - 4 = 21

=> x - 1/x = √21

Now x² - 1/x² = (x + 1/x)(x - 1/x) = 5 * √21 = 5√21.

(x² + 1/x²)(x² - 1/x²) = 23 * 5√21 = 115√21.

Answer 2

Step-by-step explanation:

x+1/× = 5

(x+1/x)^2 = (5)^2

x^2+1/x^2+2 = 25

x^2+1/x^2 = 23

(x^2+1/x^2)(x^2-1/x^2)

(23)(x+1/x)(x-1/x)

(23)(5)(√21)

527