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I cannot believe I am asking questions as stupid as this, but I know I am doing these wrong and want to correct my bad habits. My questions are on derivatives, something I used to be really good at, I'm hoping it will start to come back to me soon. Anyway here they are along with my work:

1)Differentiate square root2 *u + squareroot(3u)

For this one I used the product rule for the first section because you had root 2 multiplied by the constant 2, and for the second I just took the derivative as normal. I ended up getting an answer of:

(squareroot2 + u)/(3/2 square rootu). Sorry if this seems unclear, I don't know how to get the square root sign to show up on the computer.

2) Differentiate (u^-2 + u^-3)(u^5 - 2u^2)

For this I used to product rule of course and these were my steps:

=(u^-2+u^-3)(5u^4-4u) + (u^5-2u^2)(-2u^-3-3u^-4)

=3u^2-2u+2u^-2

I don't know where I went wrong on this one, or if I even did go wrong, but something just doesn't seem right to me.

3) y=(square root x-1)/(square root x+1)

For this one I'm not really sure how to go about showing my work on the computer so I will just write my answer. I used the quotient rule to get it.

y'=(-0.5x-x^-0.5)/(x^0.5+1)^2

Again, I do not know where I'm going wrong or if I did I'm just unsure of my answer.

4) f(x) = (ax+b)/(cx+d)

For this one I treated the a, c and d as constant values. Then I used the quotient rule to differentiate. My biggest problem with this one is that the answer seems to long to be right.

I think it might be a bit easier to show my work on this one:

=((cx+d)(x)-(ax+b)(x))/(cx+d)^2

=((x)(cx-ax+d-b))/(cx+d)^2

Thanks a lot for any help you can give guys, I know I can get this stuff eventually it just takes me awhile to get a good grasp of it sometimes. Sorry for my lack of work shown, I really don't know how to show it on the computer, and I was worried any work I did show would make it even more confusing. Thanks a lot!

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# Derivatives problem

**Physics Forums | Science Articles, Homework Help, Discussion**