Solving Integral 0 to 3 f(3t)dt Given Question Info

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There was a question on my quiz today that went something like this

the integral 0 to 5 f(x)dx = 7, the integral 1 to 5 f(x)dx = 3

given this information, solve the integral 0 to 3 f(3t)dt.

I had no idea how to do it... How can I compute f(3t)dt given this information? or does the t = x?

Thanks
 
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Think of what kind of function f(3t) is. Try to compare it with the function f(x).
 
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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