Calculate F'(x)

**450081592** · January 12th 2010, 05:04 PM

F(x) = $\int _1\,^x\!$ $sin\pi t$ dt

I know that F'(x) = f(x), but what is f(x) here? do I just sub x into $sin\pi t$ ?

**Krizalid** · January 12th 2010, 05:06 PM

Your writting is quite hard to read, better you to improve it.

Besides, it's a simple application of the FTC.

**skeeter** · January 12th 2010, 05:23 PM

Originally Posted by 450081592

$F(x) = \int _1^x \sin{\pi t} \, dt$

I know that $F'(x) = f(x)$ , but what is $f(x)$ here? do I just sub x into $\sin{\pi t}$ ?

fixed latex ...

yes ...

if $F(x) = \int_a^x f(t) \, dt$ , then $F'(x) = f(x)$

**450081592** · January 12th 2010, 05:29 PM

Originally Posted by skeeter

yes ...

if $F(x) = \int_a^x f(t) \, dt$ , then $F'(x) = f(x)$

Ya Ibut where is f(x) here? is it $sin\pi x$ ?

**mr fantastic** · January 12th 2010, 06:17 PM

Originally Posted by 450081592

Ya Ibut where is f(x) here? is it $sin\pi x$ ?

Please read post #3 again. Do you see what f(t) is? Do you know how to replace t with x to get f(x)?

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