# Fundamental Theorem of Calculus to find Derivative

1. Aug 5, 2009

### jeeves_17

Use the Fundamental Theorem of Calculus to find the derivative of the function

g(x) = $$\sqrt{x}\int sinx$$ Ln(t) $$\frac{cos(t)}{t}$$ dt

g'(x) = lnx cosx / x. By integrating this function, you receive the function g(x). Then by differentiating g(x) you receive g'(x) which is what is given, according to FTCI.

I was told I got this completely wrong. (out of 5) So looking for some help. Thanks in advance.

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Aug 5, 2009

### Дьявол

I do not understand something. Could you possibly rewrite the original problem?
Is it:

$$g(x)=\sqrt{x}\int{sin(x)dx} *\int{\frac{ln(t)*cos(t)}{t}dt}$$

Regards.

3. Aug 5, 2009

### jgens

As stated, the function $$g(x)$$ doesn't look quite right. Is it supposed to be defined such that,

$$g(x) = \sqrt x sin(x) \int_{a}^x \frac{ln(t)cos(t)}{t} \, dt$$

If so, then use the product rule of differentiation because $$g(x)$$ can be defined in terms of the product of two functions $$u$$ and $$v$$ where,

$$u = \sqrt x sin(x)$$

$$v = \int_{a}^x \frac{ln(t)cos(t)}{t} \, dt$$

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