Question

if the nth term of ap is 3n+4 then the value of a1+a9 is

please help​ it is urgent

Answer 1

Step-by-step explanation:

a9=3n+4

an=a+(n-1)d

a1=a+(1-1)d

a1=a

a1+a9=a+3n+4

Answer 2

Given :-

• aₙ = (3n + 4)

To find :-

• a₁ + a₉ = ?

Solution :-

★ nth term is given as ‘3n + 4’

For finding the first term i.e. a₁:

Just substitute the value of aₙ

aₙ = (3n + 4)

→ a₁ = 3(1) + 4

→ a₁ = 3 + 4

→ a₁ = 7

For finding the ninth term i.e. a₉:

Substitute n as 9

aₙ = (3n + 4)

→ a₉ = 3(9) + 4

→ a₉ = 27 + 4

→ a₉ = 31

Now for (a₁ + a₉)

a₁ + a₉ = 7 + 31

→ a₁ + a₉ = 38

∴ a₁ + a₉ = 38