If x, y, z ∊ R, then the value of determinant |\table (5^{\x} + 5^{-x})^2 , (5^{\x} - 5^{-x})^2 , 1 ; (6^{\x} + 6^{-x})^2, (6^{\x} - 6^{-x})^2, 1 ;(7^{\x} + 7^{-x})^2, (7^{\x} -7^{-x})^2, 1| is