8.25. y = (cos² x) / lg(x² – 2x + 1).
(u/v)`=(u`·v–u·v`)/v2 u=cos2x u`=2cosx·(cosx)`=2cosx·(–sinx)=–sin2x v=lg(x2–2x+1) v`=(1/(x2–2x+1)·ln10)·(x2–2x+1)`=(2x–2)/((x2–2x+1)·ln10)= =2/((x–1)·ln10) О т в е т. (–sin2x·lg(x2–2x+1)– 2cos2x/((x–1)·ln10))/lg2(x2–2x+1)