Question

find the sum of first 8 terms of ap whose first term is 3 and common difference is 6​

Answer 1

Step-by-step explanation:

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Answer 2

Given :-

First term = 3

Common difference = 6

To Find :-

The sum of first eight terms.

Solution :-

We know that,

• n = Number of terms
• a₁ = First term
• d = Common difference

Given that,

First term (a₁) = 3

Common difference (d) = 6

The sum of n terms of an A.P is given by the formula,

$\underline{\boxed{\sf S_n=\dfrac{n}{2}(2a+(n-1)d) }}$

Substituting their values, we get

$\sf S_8=\dfrac{8}{2} (2 \times 3+(8-1) \times 6)$

$\sf S_8 = 4 ( 6 + 42)$

$\sf S_8 = 4 \times 48$

$\sf S_8 = 192$

Therefore, the sum of the first 8 terms is 192