Question

Find the sum of the first 20terms of the ap 5,8,11,14​

Answer 1

Answer:

Hey there !!

Answer:

→ 670 .

Step-by-step explanation:

Given :-

→ a₁ = 5 .

→ a₂ = 8 .

Then, d = a₂ - a₁ .

= 8 - 5 .

=  3 .

To find :-

→ S₂₀ .

Solution :-

Sum pf nth term is given by:-

→ S_nSn = n/2 [ 2a + ( n - 1 ) d ] .

⇒ S₂₀ = 20/2 [ 2 × 5 + ( 20- 1 ) 3 ] .

= 10 [ 10 + 19 × 3 ] .

= 10 [ 10 + 57 ] .

= 10 × 67 .

∴ S₂₀ = 670 .

Hence, it is solved .

☆ I HOPE IT'S HELP YOU ☆

Answer 2

Answer:

Here

a=5, an=14 and n=20

The formula is Sn= n/2(a+l)

Now put these values in the given formula.

Sn=20/2(5+14)

Sn=10*19

Sn=190

Hence the sum of given ap is 190

I Hope that it will help you

Thank s ....