You visited us 1 times! Enjoying our articles? Unlock Full Access!

nth Term of an AP

If T n =78, w...

Question

If $T_{n} = 78$ , where $T_{n}$ denotes the $n^{t h}$ term the following AP:
3, 8, 13, 18, . . . then n = ___

Open in App

Solution

Here, first term, $a = 3$

Common difference, $d = 8 - 3 = 13 - 8 = 5$
$a_{n} = 78$
Using formula $a_{n} = a + (n - 1) d$ to find nth term of arithmetic progression, we get
$a_{n} = 3 + (n - 1) 5$ {we want to find value of n here.}
$\Rightarrow 78 = 3 + (n - 1) 5$
$\Rightarrow 75 = 5 n - 5$
$\Rightarrow 80 = 5 n$
$\Rightarrow n = \frac{80}{5} = 16$
It means $16^{t h}$ term of the given AP is equal to 78.

Suggest Corrections

Similar questions

If $T_{n} = 78$ , where $T_{n}$ denotes the $n^{t h}$ term the following AP:
3, 8, 13, 18, . . . , then n = 16

t_{n}

n^{t h}

S_{n}

n

t_{m} = \frac{1}{n}

t_{n} = \frac{1}{m}

S_{m n}

n

A P

S_{n} = (1 + 2 T_{n}) (1 - T_{n})

T_{n}

n t h

T_{2}^{2} = \frac{\sqrt{a} - \sqrt{b}}{4} (a, b ϵ N)

(a + b)

n^{t h}

T_{1} = 3

T_{n} = 96

S_{n} = 189

n

T_{n}

S_{n}

n^{t h}

n^{t h}

Join BYJU'S Learning Program