DERIVATIVE OF LOG functions ! (1 Viewer)

[darlking]

1. find the equation of the tangent to the curve y=loge(5x+4) at the point where x=3.
How do i do this? Show working out too please

First i y' it so i got...>> 5
----------
5x+4

Do i sub x=3 in now? So i will get.. 5/19.
Whats next? i think i did it wrong after this step.
I found y but its a decimal. i tried subbing in the y-y1=m(x-x1) but it came out wrong!
So i need ya help

 

[iBibah]

1. find the equation of the tangent to the curve y=loge(5x+4) at the point where x=3.
How do i do this? Show working out too please

First i y' it so i got...>> 5
----------
5x+4

Do i sub x=3 in now? So i will get.. 5/19.
Whats next? i think i did it wrong after this step.
I found y but its a decimal. i tried subbing in the y-y1=m(x-x1) but it came out wrong!
So i need ya help

Leave y as a log, not decimal.

 

[darlking]

Leave y as a log, not decimal.

Ok. So i will get, well i got y= 1oge(101/19). True?

 

[iBibah]

Ok. So i will get, well i got y= 1oge(101/19). True?

y=ln(19)
x=3
m=5/19

 

[darlking]

y=ln(19)
x=3
m=5/19

Thanks, i figured my mistake

 

[darlking]

Next Q.

Find the stationary point on the curve y= lnx/x and determine its nature. How do i dy/dx this?
AND

Find the derivative of log(little3)(2x+5) ----> I don't know if the 3 is a base or just 3 but its small and looks like a base.

 

[iBibah]

Next Q.

Find the stationary point on the curve y= lnx/x and determine its nature. How do i dy/dx this?
AND

Find the derivative of log(little3)(2x+5) ----> I don't know if the 3 is a base or just 3 but its small and looks like a base.

quotient rule...

u=ln(x)
v=x

 

[darlking]

quotient rule...

u=ln(x)
v=x

Thanks . What about Find the derivative of log(little3)(2x+5) ----> I don't know if the 3 is a base or just 3 but its small and looks like a base.

 

[Shadowdude]

Is log base 3.

 

[iBibah]

Thanks . What about Find the derivative of log(little3)(2x+5) ----> I don't know if the 3 is a base or just 3 but its small and looks like a base.

It's a base. In this case you can't differentiate, so you must put it in terms of base e. think about how to convert it to base e. (fraction of some sort).

 

[darlking]

Another q:
log(B7)2= 0.36
log(B7)5= 0.83

find log(B7)14

 

[Shadowdude]

From log laws:



So:

 

[darlking]

From log laws:



So:

Thanks !!!

 

[darlking]

Another question:
Find the derivative of:

y= (lnx)^2

Please show working out if you can

 

[darlking]

Hehehe, don't worry. I figured it out. Here's the working out:

2(1/x)(lnx) = 2lnx/x

 

[AAEldar]

This is incorrect.

but

 

[HeroicPandas]

This is incorrect.

but

AMEN..........thank you for finding my mistakes