A)
y ' = (x^7) = 7x^6
b)
y ' = (cosx/x) ' = ((cosx)'x - (x)'cosx ) / x^2 = ( - xsinx - cosx)/x^2 =
= - sinx/x - cosx/x^2
c)
y ' = (x tgx) ' = (x)' tgx + (tgx)' x = tgx + x/cos^2x
d)
y ' = (4x + 5) ' = 4(x)' + 5(1)' = 4*1 + 5*0 = 4
e)
y ' = ((3x - 4)^4)' = 4(3x - 4)^3 *(3x - 4) ' = 12 (3x - 4)^3