# edexcel further math 2 helpWatch

#1
can someone explain to me how to use method of difference? like the one in page 12 of textbook ?
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7 years ago
#2
Basically write out the first few terms of the series until you spot a pattern for canceling.
Then follow this pattern and voila!
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#3
(Original post by Potassium^2)
Basically write out the first few terms of the series until you spot a pattern for canceling.
Then follow this pattern and voila!
may i know what is the pattern like? is it when they equal the same u cancel out? and something to do with diagonal?
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7 years ago
#4
(Original post by SennaRacer77)
may i know what is the pattern like? is it when they equal the same u cancel out? and something to do with diagonal?
Consider the sum

The idea is to find terms which cancel and see which are left.. so we consider different vaules of r:

...

You should be able to see that the half will cancel, the thirds will cancel. Also, although we haven't written it, the quarter will also cancel (if you imagine writing out the line for r=4)

As we continue to r=n, you should see that the 1/n will also cancel. Also, if you imagine writing out the line r=n-2, we would find that the 1/(n-1) would also cancel. Leaving us with only 2 terms. And so our summation becomes:

In other words, for this summation, whatever the value of n in the , the sum will equal
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#5
(Original post by dknt)
Consider the sum

The idea is to find terms which cancel and see which are left.. so we consider different vaules of r:

...

You should be able to see that the half will cancel, the thirds will cancel. Also, although we haven't written it, the quarter will also cancel (if you imagine writing out the line for r=4)

As we continue to r=n, you should see that the 1/n will also cancel. Also, if you imagine writing out the line r=n-2, we would find that the 1/(n-1) would also cancel. Leaving us with only 2 terms. And so our summation becomes:

In other words, for this summation, whatever the value of n in the , the sum will equal
thanks man! i knida get the picture. if i need anything will let ya know
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7 years ago
#6
(Original post by SennaRacer77)
thanks man! i knida get the picture. if i need anything will let ya know
No problem
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#7
btw,
im stuck at FP2 exercise 5E, page 99, i use my particular integral as lamda e^x and i get lamda=1, but i cant seem to get the answer :/

and exercise 5D page 97 i need help with that too :/
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