lny=ln(x-1)+2ln(x-2)+3ln(x-3)+4ln(x-4)
y'/y=1/(x-1)+ 2/(x-2) +3/(x-3) +4/(x-4)
∴y'=(x-2)²(x-3)^3(x-4)^4 +2(x-1)(x-2)(x-3)^3(x-4)^4 +3(x-1)(x-2)^2(x-3)^2(x-4)^4
+4(x-1)(x-2)²(x-3)³(x-4)³
lny=ln(x-1)+2ln(x-2)+3ln(x-3)+4ln(x-4)
y'/y=1/(x-1)+ 2/(x-2) +3/(x-3) +4/(x-4)
∴y'=(x-2)²(x-3)^3(x-4)^4 +2(x-1)(x-2)(x-3)^3(x-4)^4 +3(x-1)(x-2)^2(x-3)^2(x-4)^4
+4(x-1)(x-2)²(x-3)³(x-4)³