Question

1,-2,-5,-8.........-179 how many terms are there in ap

Answer 1

Answer:-

61

Step by step explanation

Given AP : 1 , - 2 , - 5 , - 8,....... - 179

First term, a = 1

Common Difference, d = ( a2 - a1 ) = - 2 - 1 = - 3

Last term, an = - 179

We know that the nth term of an AP :

an = a + ( n - 1 )* d

=> - 179 = 1 + ( n - 1 ) * ( - 3 )

=> - 179 = 1 - 3n + 3

=> - 179 = 4 - 3n

=> 3n = 4 + 179

=> 3n = 183

=> n = 183 / 3

=> n = 61

Hence, there are 61 terms in this AP.

Hope it helps!

Answer 2

Answer:

Given that

1 , -2 , -5 , -8 , ............. , -179

First term a = 1

Common difference

d = a2 - a1 = -2 -1 = -3

d = -3

Last term añ = -179

nth term of A.P

añ = a + ( n - 1 ) d

-179 = 1 + ( n - 1 ) -3

-179 = 1 + ( - 3n + 3 )

-179 = 1 - 3n + 3

-179 = 4 - 3n

3n = 4 + 179

3n = 183

n = 183 / 3

n = 61