y'=(8(lncos5x)⁷)'=8*7(lncos5x)⁶*(lncos5x)'=56(lncos5x)⁶*(1/cos5x)*(cos5x)'=
56(lncos5x)⁶*(1/cos5x)*(-sin5x)*(5x)'=
56(lncos5x)⁶*(1/cos5x)*(-sin5x)*(5)=-280(tg5x)*(lncos5x)⁶
y'=(8(lncos5x)⁷)'=8*7(lncos5x)⁶*(lncos5x)'=56(lncos5x)⁶*(1/cos5x)*(cos5x)'=
56(lncos5x)⁶*(1/cos5x)*(-sin5x)*(5x)'=
56(lncos5x)⁶*(1/cos5x)*(-sin5x)*(5)=-280(tg5x)*(lncos5x)⁶