Question

plz help this girl. ​

Answer 1

If x - 1/x = 3

Squaring on both sides

• (x - 1/x)² = 9

Using identity (a-b)² = a² + b² - 2ab.

Back to the question

• x² + 1/x² - 2 = 9

Shift 2 on RHS where it's worth to be place !!

• x² + 1/x² = 11.

Again Squaring on both side

• (x²+1/x²)² = 121
• x⁴ + 1/x⁴ + 2 = 121.
• x⁴ + 1/x⁴ = 121 - 2
• x⁴ + 1/x⁴ = 199