Subjective Type

$$\displaystyle { a }_{ n }=n(n+2)$$

Solution

Given, $$a_n=n(n+2)$$
Substituting $$n=1, 2, 3, 4,5,$$ we obtain
$$\displaystyle {a}_{1} = 1 (1+2) = 3,\\{a}_{2} = 2 (2+2) = 8,\\
{a}_{3} = 3 (3+2) = 15,\\
{a}_{4} = 4 (4+2) = 24,\\
{a}_{5} = 5 (5+2) = 35. $$

SIMILAR QUESTIONS

Sequences and Series

Given an A.P. whose terms are all positive integers. The sum of its first nine terms is greater than $$200$$ and less than $$220$$. If the second term in it is $$12$$, then $$4^{th}$$ term is :

Sequences and Series

Let X be the set consisting of the first $$2018$$ terms of the arithmetic progression $$1, 6, 11,$$______, and Y be the set consisting of the first $$2018$$ terms of the arithmetic progression $$9, 16, 23$$, ________. Then, the number of elements in the set X$$\cup$$Y is _______?

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$$\displaystyle{ a }_{ n }=n\frac { { n }^{ 2 }+5 }{ 4 } $$

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$$\displaystyle{ a }_{ n }=4n-3;{ a }_{ 17 },{ a }_{ 24 }$$

Sequences and Series

$$\displaystyle { a }_{ n }=\frac { { n }^{ 2 } }{ { 2 }^{ n } } ;{ a }_{ 7 }$$

Sequences and Series

$$\displaystyle{ a }_{ n }=({ -1 })^{ n-1 }{ n }^{ 3 };{ a }_{ 9 }$$

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