Question

if x =4-√15, find value of x⁴+1/x⁴​

Answer 1

Answer:

3842

Step-by-step explanation:

x= 4-√15

=> x² = 31 - 8√15

=> x⁴ = 961+64×15 - 496√15

=> x⁴ = 1921 - 496√15...............(1)

again

1/x= 1/(4-√15) = 4+√15 when rationalizing

=> 1/x²= 31+8√15

=> 1/x⁴ = 1921+496√15........(2)

adding (1) and (2)

=> x⁴+1/x⁴ = 1921+1921

= 3842

Answer