Question

Find the 18th term of A.P 7,13,19,25​

Answer 1

Solution:-

Given series is

:- 7 , 13 , 19 , 25 , ...........

First term

:- a = 7

Common difference

:- a₂ - a₁ => 13 - 7 = 6

Number of term

:- n = 18

Formula

:- Tₙ = a + ( n - 1 )d

Now

=> T₁₈ = 7 + ( 18 - 1 ) × 6

= 7 + 17 × 6

= 102 + 7

= 109

So 18 th of ap is 109

More about AP

A sequence of numbers is called an Arithmetic progression 

if the difference between any two consecutive terms is always the same. In simple terms, it means that the next number in the series is calculated by adding a fixed number to the previous number in the series.

For example, 2, 4, 6, 8, 10 is an AP because difference between any two consecutive terms in the series (common difference) is same (4 – 2 = 6 – 4 = 8 – 6 = 10 – 8 = 2)

Answer 2

${\bold{\blue{\boxed{\bf{Given}}}}}$

• first term = a = 7
• common diff. = d = 6
• no. of term =n= 18

${\bold{\blue{\boxed{\bf{To\:find}}}}}$

• $\bold{a_{18}}= ???$

${\bold{\blue{\boxed{\bf{ Formulae\:used }}}}}$

$\bold a_n = a + (n-1)d$

${\bold{\blue{\boxed{\bf{ solution }}}}}$

$a_{18} = 7 + (18 -1)\times 6$

$a_{18} = 7 + 17 \times 6$

$a_{18} = 7 + 102$

$a_{18} = 109$

${\bold{\blue{\boxed{\boxed{\bf{a_{18} = 109}}}}}}$