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# Core 2 - Trapezium rule question watch

1. The question is :
http://gyazo.com/f87c292be7e205cff80fb4437ab34b29

I know what the trapezium rule is but on the mark scheme there is a random 2 at in the equation after the 22+28

http://gyazo.com/524c2f5556e478c6141ce4c4a09e1824

Can some one explain why that is there because i thought that it was meant to be only y0 + yn nothing else.
2. you are right in saying it is y0+yn but you also need the strips that you are adding, this is where the 2 comes in. All the strips that you will need to use are timed by 2

the actual equation is
0.5*(a+b)(y0+yn+2[y1+y2+y3....Yn-1])
in other words
0.5*width of strip (first height+last height + 2[sum of the strips used]).

this should explain it more-
http://www.examsolutions.net/maths-r...tutorial-1.php

Hope it helps
3. (Original post by mikeabc)
you are right in saying it is y0+yn but you also need the strips that you are adding, this is where the 2 comes in. All the strips that you will need to use are timed by 2

the actual equation is
0.5*(a+b)(y0+yn+2[y1+y2+y3....Yn-1])
in other words
0.5*width of strip (first height+last height + 2[sum of the strips used]).

this should explain it more-
http://www.examsolutions.net/maths-r...tutorial-1.php

Hope it helps
Thanks you so much mate
4. (Original post by mikeabc)
you are right in saying it is y0+yn but you also need the strips that you are adding, this is where the 2 comes in. All the strips that you will need to use are timed by 2

the actual equation is
0.5*(a+b)(y0+yn+2[y1+y2+y3....Yn-1])
in other words
0.5*width of strip (first height+last height + 2[sum of the strips used]).

this should explain it more-
http://www.examsolutions.net/maths-r...tutorial-1.php

Hope it helps
½×10×(28+22+2[19+14+11+12+16]) Doesnt get me the right answer which is 720m
5. According to the mark scheme that you included, the answer is 970 which is what the calculation works out to be.
6. (Original post by Timmy12321)
½×10×(28+22+2[19+14+11+12+16]) Doesnt get me the right answer which is 720m
i typed this in to the calculator and got the right answer, you sure you may have not any bracket errors??

a good tip i do is to add all the values in the 2[19+14+11+12+16] and times it by 2
then add this to the 28+22.
Then work out the 0.5*10 bit

this should give you the right answer

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Updated: May 16, 2013
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