True or false questions about line/surface integral

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Homework Statement


if f has a continuous partial derivatives on R^3 and c is any circle ,then the integral of gradient f dot dr over c is zero

integral of f(x,y) ds over -c= - integral of f(x,y) ds over c


Homework Equations





The Attempt at a Solution



if the condition is not mentioned, then that statement is usually wrong
so i guess the second one is wrong
not quite sure about the first one
 
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For (1), think about "Green's theorem". Does it apply here?

For (2), the "conditions" are that the function be integrable. Which it is because the question give \int f(x) dx.
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
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