Question

7+14+21+28+......70 , find nth term.

Answer 1

Hii ☺ !!





AP = 7 , 14 , 21 , 28 , .......... , 70



Here,


First term ( a ) = 7


Common difference ( d ) = 14-7 = 7



And,

Last term ( Tn ) = 70


a + ( n - 1 ) × d = 70


7 + ( n - 1 ) × 7 = 70



7 + 7n - 7 = 70


7n = 70


n = 10

Answer 2

according to questions

given number in AP terms :-

7 ,14 ,21 ,28.........70

first term (a) = 7

common difrence(d) = ( a2 - a1 )

( a2 - a1 ) = 14 - 7 = 7

d = 7

a = 7 , d = 7

here last term is 70.

Tn = 70

a + ( n - 1 ) d = 70

7 + ( n - 1 ) 7 = 70

7 + 7 n - 7 = 70

7 - 7 +7n = 70

7n = 70

$n = \frac{70}{7} = 10 \\ \\n = 10 \\ \\ \mathfrak{solution} \: = \boxed {10} \:$