solve for this please

Question

2 sec³(x) − 2 sec²(x) − 2 sec(x) + 2

Answer 1

0 = 2 U^3 - 2U^2 - 2U + 2 where U = sec x

= U^3 - u^2 - U + 1

= U^2(U-1) - (U-1)

= (U-1) (U^2 - 1)

= (U-1)(U+1)(U-1)

= (U+1)(U-1)^2

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U=-1 or U=1

sec x = -1 or sec x = 1

cos x = -1 or cos x = 1

integral multiples of pi, pi * n where n is an integer