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Mathematics 7 Online
OpenStudy (anonymous):

Calculus 2

OpenStudy (anonymous):

OpenStudy (anonymous):

I'm certain it's not the first or the last

OpenStudy (anonymous):

@zepdrix

zepdrix (zepdrix):

Closed. Did you figure this one out already? :o

OpenStudy (anonymous):

I don't think so. If you have any idea, please

zepdrix (zepdrix):

Oh I see :)

zepdrix (zepdrix):

Hmm I can't figure out what's going on with this one. I'm thinking we could estimate the derivative at certain points like this:\[\Large\bf\sf f'(x_1)\quad\approx\quad \frac{f(x_1)-f(x_o)}{x_1-x_o}\]But the numbers aren't working out right.. hmmm

zepdrix (zepdrix):

\[\Large\bf\sf f'(2)\quad\approx\quad \frac{f(2)-f(0)}{2-0}\]Solving for f(2),\[\Large\bf\sf f(2)\quad\approx\quad 2f'(2)+f(0)\]

zepdrix (zepdrix):

But that gives us like ... 117 +_+ no bueno.. hmmm

zepdrix (zepdrix):

Using Linear Approximation should give us:\[\Large\bf\sf f(2)\quad\approx\quad f(0)+f'(0)(2-0)\]\[\Large\bf\sf f(2)\quad\approx\quad 39+23\cdot2\quad\approx\quad 85\]

zepdrix (zepdrix):

Hmm weird, I'm not sure how they want you to approximate this... any ideas Ralph? :[

zepdrix (zepdrix):

XD

zepdrix (zepdrix):

It seems like what they're doing is:\[\Large\bf\sf f(2)\quad\approx\quad f'(0)+2f(0)\quad=\quad 23+2\cdot39\quad=\quad 101\]Which is one of the options for the first approximation. But it doesn't seem to make sense to me... Hmmmm.

zepdrix (zepdrix):

@ranga :D

OpenStudy (ranga):

To get to f(x) from f'(x) we need to integrate f'(x) which is same as finding the area under the curve and adding it to f(0). f(2) = f(0 + area under the curve of f'(x) between x = 0 and x = 2.

zepdrix (zepdrix):

So as OOPS posted earlier (and erased):\[\Large\bf\sf \int\limits_0^2 f'(x)\;dx\quad=\quad f(2)-f(0)\]Then solving for f(2),\[\Large\bf\sf f(2)\quad=\quad f(0)+\int\limits_0^2f'(x)\;dx\]And then we're uhh..... approximating this area how? Treating it as a rectangle or triangle or something maybe?

OpenStudy (ranga):

Maybe the average of lower and upper Riemann sum?

OpenStudy (ranga):

f(0) = 39 f(2) = 39 + 1/2 * (23+39) * 2 = 39 + 62 = 101. 23 * 2 is the lower bound of the area evaluated at the left end and 39 * 2 is the upper bound of the area evaluated at the left end and

zepdrix (zepdrix):

Oh oh maybe this:|dw:1390009096612:dw|Apply trapezoid rule to approximate?

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