The Simpsons (1 Viewer)

fullonoob

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L = is the lenth of the arc of curve y = f(x) between x = a and x = b. Usig Simpson' rule with five function values, estimate the length of the graph y =x^2 between x = 0 and x =2. Answer correcto two dp.
thx
 
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life92

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Okay so notice how the length of the arc is
S (a=>b) [1+{f'(x)}^2]^(1/2)

Since we're concerned with the function y = x^2
f'(x) = 2x
[f'(x)]^2 = 4x^2

So the function we are concerned with for Simpsons rule will become
[1+4x^2]^(1/2).

Now Simpsons rule is
A = h / 3 [ y0 + 4y1 + 2y2 + 4y3 + ... yn ]
where h is the distance between the x values

Since it asks for 5 function values, we take the values of x as 0, 0.5, 1, 1.5 and 2
So we sub this into the equation, and h becomes 0.5

L = 0.5 / 3 [ {1+0}^(1/2) + 4{1+4(0.5)^2}^(1/2) + 2{1+4(1)^2}^(1/2) + 4{1+4(1.5)^2}^(1/2) + {2+0}^(1/2) ]
Put those into a calculator and you should get the correct answer.
 

fullonoob

fail engrish? unpossible!
Joined
Jul 19, 2008
Messages
465
Gender
Male
HSC
2010
Okay so notice how the length of the arc is
S (a=>b) [1+{f'(x)}^2]^(1/2)

Since we're concerned with the function y = x^2
f'(x) = 2x
[f'(x)]^2 = 4x^2

So the function we are concerned with for Simpsons rule will become
[1+4x^2]^(1/2).

Now Simpsons rule is
A = h / 3 [ y0 + 4y1 + 2y2 + 4y3 + ... yn ]
where h is the distance between the x values

Since it asks for 5 function values, we take the values of x as 0, 0.5, 1, 1.5 and 2
So we sub this into the equation, and h becomes 0.5

L = 0.5 / 3 [ {1+0}^(1/2) + 4{1+4(0.5)^2}^(1/2) + 2{1+4(1)^2}^(1/2) + 4{1+4(1.5)^2}^(1/2) + {2+0}^(1/2) ]
Put those into a calculator and you should get the correct answer.
YAYAYAY thanks :) you did minor error though (in bold)
damn i subbed in y values instead of x....silly me
 

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