Question

The value of S3 in the Arithmetic Progression 7,4, 1, -2​

Answer 1

Step-by-step explanation:

Sum to n terms => n/2[2a+(n-1)d]

here, n=3

so, put the value of n

=>3/2[2×7-6]

=>3/2(8)

=>12

Answer 2

Answer:

a = 7 , d = a2 - a1 , n = 3

= 4 - 7

= - 3

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

= 3/2 [2×7 + (3 - 1) - 3]

= 3/2 [14 + 2× -3 ]

= 3/2 [14 + (-6) ]

= 3/2 × 8

= 3 × 4

S3 = 12

thank you