Question

please answer a simple question if in series. 1+2+3+4+5+...(upto n terms) then what does the three dot represents?

Answer 1

These three dots are representing the number of term.In the brackets number of terms is written, there are n terms.

So,

First term = a = 1

Common Difference = d

                         = any term - previous term

                         = 5 - 4 = 4 - 3 = 3 - 2 = 2 - 1

                         = 1

last term = $a_{n}$ = ?

 We know,

$a_{n} = a+(n-1)d$

$a_{n} = 1 + (n-1)(1)$

$a_{n}=1+n(1)-1(1)$

$a_{n}=1+n-1$

$a_{n}=n$

Therefore, n th term of the AP is n.

Answer 2

$\huge \bold {\mathfrak {hey}}$

✔️ These 3 dots represents the number of terms written.

➡️ There are n terms given

First term => a

Common difference => d


We know that,



➡️ ann = a +(n - 1)d


➡️ a n = 1 + n(1) - 1(1)


➡️ a n = 1 + n - 1


➡️ a n = n

Therefore, n th pf the A. P is n.


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