Question

1. The first term of an arithmetic sequence is 3 and the common difference is 2.What is its 10th term?

(34,89,45,67)​

Answer 1

Answer:

a = 3

d = 2

n = 10

using the formula = An = a+(n-1)d

An = 3+(10-1)×2

An = 3+18

An = 21 ✓

21 will be the 10th of this AP....

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Answer 2

Given :

First term of an arithmetic sequence is 3 .

Common difference is 2 .

To Find :

10th term

Solution :

$\longmapsto\tt{First\:term\:(a)=3}$

$\longmapsto\tt{Common\:difference\:(d)=2}$

$\longmapsto\tt{No\:of\:terms\:(n)=10}$

Using Formula :

$\longmapsto\tt\boxed{{a}_{n}=a+(n-1)\times{d}}$

Putting Values :

$\longmapsto\tt{{a}_{10}=3+(10-1)\times{2}}$

$\longmapsto\tt{{a}_{10}=3+(9)\times{2}}$

$\longmapsto\tt{{a}_{10}=3+18}$

$\longmapsto\tt\bf{{a}_{10}=21}$

So , The 10th term of the sequence is 21 .

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$\tt{{a}_{n}=a+(n-1)\times{d}}$

$\tt{{s}_{n}=\dfrac{n}{2}[2a+(n-1)\times{d}}$

$\tt{{s}_{n}=\dfrac{n}{2}\:[a+l]}$

Here :

a = first term

d = common difference

n = number of terms

l = last term

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