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permutations and combinations

the number of arrangements of the word "DELHI" in which E precedes I is

Note by Rama Rao
2 years, 10 months ago

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There are \(5!\) ways to arrange the letters. Each permutation where E comes before I has a pair where E comes after I (namely swap E and I), so the number of permutations where E comes before I is exactly half of it, or \(5!/2 = 60\). Ivan Koswara · 2 years, 10 months ago

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If f is a differentiable function and f(x^2-y^2 )=xf(x)-yf(y)  and f(1)=2,then find f(2).
Rama Rao · 2 years, 8 months ago

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@Rama Rao If x^2015/2015+x^2014/2014+x^2013/2013+⋯+x+1=0, find the number of real roots. Rama Rao · 2 years, 5 months ago

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