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junior college 1 | H2 Maths
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Yong Xin Yu
Anonymous

junior college 1 chevron_right H2 Maths chevron_right Singapore

Help is needed asap for part (ii), thanks in advance

Date Posted: 4 years ago
Views: 343
Eric Nicholas K
Eric Nicholas K
4 years ago
The denominator is (r - 1) (r) (r + 1), all of which is 1 less than (r) (r + 1) (r + 2)

So you can consider using substitutions like r = k + 1 which now makes the denominator (k) (k + 1) (k + 2).

But if r = k + 1, then r = 2 in the lower limit becomes k = 1 in be lower limit and N in the upper limit goes down by 1 as well to become N - 1.

This is equivalent to the original given expression in the question, except that we replace all N by N - 1.

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Tham KY
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