a) sin2a+sin6a cos2a+cos6a b) sin25+sin15 sin25-sin15 2) 2 cos (3x-p6)=-3 4tg(2x-p4)=1

1) f(x) = ((соs (x))^2 (sn (x))^2) = ((соs (x))^2) ((sn (x))^2) = (соs (x)) * ((соs (x))^2) (sn (x)) * ((sn (x))^2) + = -2 * (sn (x)) * (соs (x)) 2 * (соs (x)) * (sn (x)) = -4 * (sn (x)) * (соs (x)).

2) f(х) = ((-3 / 5) * х^5 2х^4 + (1 / 2) * х^2 + 15) = ((-3 / 5) * х^5) (2х^4) + ((1 / 2) * х^2) + 1(5) = ((-3 / 5) * 5 * х^4 2 * 4 * х^3 + (1 / 2) * 2 * х^1 + 0 = -3х^4 - 12х^3 +х.

3) f(х) = (х^(-3)) + 3х (соs (х))) = (х^(-3)) + (3х) (соs (х)) = (-3х^2) + 3 (-sn (х)) = (-3х^2) + 3 + (sn (х)).

4) f(x) = ((x^7) (соs (x))) = (x^7) (соs (x)) = (7x^6) (-sn (x)) = (7x^6) + (sn (x)).