Question

find the 20th term of an A.S -2,-5,-8 ​

Answer 1

Answer:

-59

Step-by-step explanation:

a= -2

d= -5-(-2) = -5+2 = -3

20th term = a+(n-1)d

= -2-(20-1)3

= -2-19×3

= -2-57

= -59

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Answer 2

Answer :-

The 20ᵗʰ term of Arithmetic sequence

-2, -5, -8 ... is -59.

Step-by-step explanation:

To Find :-

• The 20ᵗʰ term of an A.S.

★ Solution

Given that,

Arithmetic sequence = -2, -5, -8 ...

Firstly, finding the common difference and the first term of the sequence :-

Common difference

→ (- 5) - (- 2) = - 3

→ (- 8) - (- 5) = - 3

First term

→ First term of the given sequence is - 2.

_____________________________

Now, According the question,

We know,

tₙ = a + (n - 1) d

Where,

• tₙ = nth term
• a = first term
• n = number of terms
• d = common difference.

Therefore,

⇒ tₙ = a + (n - 1)d

⇒ t₂₀ = -2 + (20 - 1)-3

⇒ t₂₀ = -2 + 19*(-3)

⇒ t₂₀ = -2 + (-57)

⇒ t₂₀ = -2 - 57

⇒ t₂₀ = - 59

Hence,

The 20ᵗʰ term of the Arithmetic sequence is -59.

Formula used :-

• tₙ = a + (n - 1) d

NOTE:

→ tₙ = nth term

→ a = first term

→ n = number of terms

→ d = common difference.