finding deravitive

[rubing]

Hello again folks!

I am trying to find f'(x) for f(x) = ⎷(ax + b)


I can work out the following:

?y + y = ⎷[a * (x + ?x) + b]

?y = ⎷[a * (x + ?x) + b] - ⎷(ax + b)

?y = ⎷(ax + a?x + b) - ⎷(ax + b)

?y = (ax + a?x + b)^1/2 - (ax + b)^1/2

?y/?x = [(ax + a?x + b)^1/2 - (ax + b)^1/2] / ?x


At this point, I want to say that you have to multiply the numerator by something like (ax - b)^1/2, but am not really sure. all help appreciated. thanks again great calculus people!!

 

[tkhunny]

You have something like this: \(\displaystyle \frac{Z - T}{F}\)

Try the "conjugate" idea: \(\displaystyle \frac{Z - T}{F}\cdot\frac{Z + T}{Z + T}\)

See what happens.

 

[rubing]

advice taken. thx so much tk!