Question

the mean of x and 1/x is m then the mean of x^2 and 1/x^2 is km^2-1 then k is equal to
A)1
B)3
C)4
D)2

Answer 1

(x+1/x)/2=m
x+1/x=2m
${x}^{2} + 1 \div {x}^{2} + 2 =4 {m}^{2} \\( k { m}^{2} - 1) \div 2+ 2 =4 {m}^{2} \\ \\ (k {m}^{2} - 1)2 = 4{m}^{2} - 2 \\ ( 2k{x}^{2} - 2) =4{m}^{2} - 2\\ 2k =4= \frac{4}{2}$
k=2