Question

the first term of AP is 6 & common difference is 3 find S3​

Answer 1

Answer:

First Term=a=6.

Common Difference=d=3.

n=3.

S3=?.

Sn=n/2[2a+(n-1)d].

S3=3/2[2(6)+(3-1)(3)].

S3=3/2[12+(2)(3)].

S3=3/2[12+6].

S3=3/2[18].

S3=3[9].

S3=27.

I think this is your answer.

Answer 2

Given :-

• First term ( a ) = 6
• Common difference ( d ) = 3

We need to find :-

• S₃ ( Sum of first 3 terms ) = ?

Solution :-

As we know that ,

• Sn = n/2 [ 2a + ( n - 1 ) d ]

Here ,

• n is no. of terms = 3
• a is first term = 6
• d is common difference = 3

Substituting we have ,

⇒ S₃ = 3/2 [ 2(6) + ( 3 - 1 ) ( 3 ) ]

⇒ S₃ = 3/2 [ 12 + 2 ( 3 ) ]

⇒ S₃ = 3/2 [ 12 + 6 ]

⇒ S₃ = 3/2 [ 18 ]

⇒ S₃ = 3 × 9

⇒ S₃ = 27

Hence , sum of three terms [ S₃ ] = 27