Question

find the derivative : f(x)=-5lnx

Answer 1

the derivative of ln(x) is 1/x and this is something you should memorize or write on a cheatsheet (or notecard)

Answer 2

you pull out the constant, so you ignore that for now and derive ln(x) to get 1/x

then you reintroduce the constant back in

Answer 3

alright i've seen that I just dont understand how it plays in with the -5

Answer 4

that's a constant that can be ignored when you derive

Answer 5

any constants can be pulled out

Answer 6

so you would derive

y = 22*ln(x),

y = 18*ln(x)

y = -33*ln(x)

all the same way

Answer 7

ooooooohhh okay

Answer 8

-5*1/x

Answer 9

which becomes -5/x

Answer 10

you got it

Answer 11

It'd be nice if my text would've just said that instead of going around in circles

Answer 12

it probably did somewhere, but it just gave a convoluted way of saying it (with lots of notation attached)

Answer 13

If k = constant and U = expression is x, then
d/dx(kU) = k * d/dx(U)
d/dx(-5lnx) = -5* d/dx(lnx) = -5 * (1/x) = -5/x