If x= 1 2 ( 7 + 1 7 ) , then x^2-1 x- x^2-1 is equal to

Step-by-step solution

Given that, aligned x & = 1 2 ( 7 + 1 7 ) x^2 & = 1 4 (7+ 1 7 +2 )= 1 4 ( 64 7 ) & = 16 7 aligned Now, aligned x^2-1 x- x^2-1 & = x^2-1 x- x^2-1 (x+ x^2-1 ) (x+ x^2-1 ) & = x x^2-1 +x^2-1 1 & = 1 2 ( 7 + 1 7 ) 16 7 -1 + 16 7 -1 & = 1 2 ( 7 + 1 7 ) 3 7 + 9 7 & = 1 2 (3+ 3 7 )+ 9 7 & = 1 2 ( 24 7 )+ 9 7 = 21 7 & =3 aligned