Răspuns :
[tex]\displaystyle \frac{sin^6x+cos^6x-1}{sin^4x+cos^4x-1} =\\
= \frac{(sin^2x)^3+(cos^2x)^3-1}{(sin^2x+cos^2x)^2-2sin^2xcos^2x-1}=\\
= \frac{(sin^2x+cos^2x)[(sin^2x)^2-sin^2xcos^2x+(cos^2x)^2]-1}{-2sin^2xcos^2x}=\\
= \frac{(sin^2x+cos^2x)^2-3sin^2xcos^2x-1}{-2sin^2xcos^2x} =\\
= \frac{-3sin^2xcos^2x}{-2sin^2xcos^2x} = \frac{3}{2} [/tex]