Question

plz guys answer this question....

Answer 1

we take a common x/x ( x^3+1/x^3) =47

Answer 2

Step-by-step explanation:

x^4 + 1/x^4 = 47

(x ^2 + 1/x^2) ^2 = x^4 + 1/x^4 + 2

[using the identity: (a+b)^2 = a^2 + b^2 + 2ab]

(x ^2 + 1/x^2) ^2 = 47 + 2 = 49

x^2 + 1/x^2 = √49 = ±7.

Lets take the positive value , that is , 7

Now,

[x + 1/x]^3 = x^3 + 1/x^3 + 3*x*1/x*[x + 1/x]

[Using the identity: (a+b)^3 = a^3 + b^3 + 3a*b*(a+b) ]

7³ =  x³ + 1/x³ + 3*7

343 = x³ + 1/x³ + 21

x³ + 1/x³ = 343 - 21 = 322

[Had we taken the value as '-7' the answer to x³ + 1/x³ wud have been -322]