Question

In an AP, if d=-4,n=17,an=4 then a is:-
(1)6
(2)7
(3)20
(4)28​

Answer 1

Question :-

• In an A.P if d = -4, n = 7 and aₙ = 4. Find the value of a ?

Solution :-

aₙ = a + (n - 1)d

Where :

aₙ = Sum of n terms of the A.P

a = First term

n = Number of terms

d = Common difference

Substituting :

4 = a + (7 - 1) × -4

4 = a + (6) × -4

4 = a + (-24)

a + (-24) = 4

a - 24 = 4

a = 4 + 24

a = 28

∴ The value of a (First term) is 28.