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differentiation question watch

1. find the co-ordinates and the nature of any stationary points on each of the following curves:
y=4x-5e^x
2. (Original post by elvss567)
find the co-ordinates and the nature of any stationary points on each of the following curves:
y=4x-5e^x
Which bit is your problem? I'm sure that you know that you find stationary points by setting dy/dx equal to zero - it is dy/dx that is the problem? Solving dy/dx = 0? Finding the nature of the points you have already got? We need more to go on to help you!
3. (Original post by Pangol)
Which bit is your problem? I'm sure that you know that you find stationary points by setting dy/dx equal to zero - it is dy/dx that is the problem? Solving dy/dx = 0? Finding the nature of the points you have already got? We need more to go on to help you!
i got up to dy/dx= 4 - 5e^x.
0=4-5e^x
4=5e^x
then what do i do??
4. (Original post by elvss567)
i got up to dy/dx= 4 - 5e^x.
0=4-5e^x
4=5e^x
then what do i do??
All fine so far. Rearrange to get e^x = ... Now - how do you go from e^x = ... to x = ... ?
5. (Original post by Pangol)
All fine so far. Rearrange to get e^x = ... Now - how do you go from e^x = ... to x = ... ?
inverse of e^x = lnx
so do i ln both sides?
6. (Original post by elvss567)
inverse of e^x = lnx
so do i ln both sides?
Yes - but it will be much easier if you already have the equation in the form e^x = ... first.
7. (Original post by Pangol)
Yes - but it will be much easier if you already have the equation in the form e^x = ... first.
thankyou so much for the help!!

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