Hi,

I'm mistified about where I'm going wrong here:

Find the derivative of: [(4x-1)(4x-1)^1/2]

The answer given is 6(4x-1)^1/2

but I get 6(4x -1)

not sure where i'm going wrong if anyone could help that would be great!

Thanks.

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- May 21st 2009, 11:49 AMAntDifferentiation problem
Hi,

I'm mistified about where I'm going wrong here:

Find the derivative of: [(4x-1)(4x-1)^1/2]

The answer given is 6(4x-1)^1/2

but I get 6(4x -1)

not sure where i'm going wrong if anyone could help that would be great!

Thanks. - May 21st 2009, 12:06 PMskeeter
- May 21st 2009, 12:12 PMAnt
Thanks, that makes perfect sense.

could you explain what's wrong with my method please?

u = 4x-1

u' = 4

v = (4x-1)^1/2

v' = 2/[(4x-1)^1/2]

using product rule --

4(4X-1)1/2 + 2(4x-1)/[(4x-1)^1/2]

multiplying through by (4x-1)^1/2

4(4x-1) + 2(4x-1) = 24x-6 = 6(4x-1)

I know i'm going wrong somewhere..I just can't see where! - May 21st 2009, 01:46 PMskeeter
- May 21st 2009, 01:53 PMAnt
thanks, of course!

I thiink I was trying to treat the plus sign like it was an equals sign...