Question

find the sum of 20 terms of an ap 5,8,11....

Answer 1

Ans =670

A =5 first term of ap d =3 difference of a2 a1

Answer 2

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:-

→ $S_n$ = 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 .

THANKS

#BeBrainly.