If a and b be the coefficients of x 4 and x 2 respectively in the expansion of ( ) ( ) 6 6 2 2 xx xx + – +- – 1 1 , then:

If $\alpha$ and $\beta$ be the coefficients of $x^{4}$ and $x^{2}$ respectively in the expansion of

$$

\left(x+\sqrt{x^{2}-1}\right)^{6}+\left(x-\sqrt{x^{2}-1}\right)^{6} \text {, then: }

$$