4. f(x)=u/v u=√x²-9 u'=1/2√x²-9 v=x-4 v'=1
f'(x)=[u'v-v'u]/v²=[1/2√(x²-9)*(x-4)-1*√(x²-9)]/(x-4)²
5. f(x)=√x²+6x+4/x²-3x+1 u=√(x²+6x+4) u'=1/2√(x²+6x+4)
v=(x²-3x+1) v'=(2x-3)
f'(x)=[1/2√(x²+6x+4)*(x²-3x+1)-(2x-3)*√(x²+6x+4)]/(x²-3x+1)²
6. f(x)=log₅¹⁰(3x+1)
f'(x)=10log₅⁹(3x+1)*1/3x*1/ln5*3