Question

question 13................

Answer 1

(x+1/x)=10

⇒(x+1/x)²=10²

⇒x²+1/x²+2=100

⇒x²+1/x²= 100-2=98

(x-1/x)²=x²+1/x²-2

⇒(x-1/x)²= 98-2

⇒x-1/x=√96

⇒(x+1/x)(x-1/x)=x²-1/x²

⇒10x√96=x²-1/x²

∴x²-1/x²=10√96