Find the sum of the first 12 terms of the sequence. 1, -4, -9, -14, . . (2 points)

sum of the first 12 terms of the sequence. 1, -4, -9, -14, . . = -318

Step-by-step explanation:

The given AP is,

1, -4, -9, -14, . . .

first term a = 1,

common difference d = -4 - 1 = -5

number of terms  n = 12

Equation:

Sum of n terms of AP, S₁₂ = n/2[2a + (n - 1)d]

S₁₂ = 12/2[(2*1) + (12 - 1)*(-5)]

S₁₂ = 6[2 + (11*(-5))]

S₁₂ = 6[2 - 55] = 6*(-53) = -318

Therefore sum of the first 12 terms of the sequence. 1, -4, -9, -14, . . = -318

3

step-by-step explanation:

step-by-step explanation:

4  

25

5258y

54.

t5

5r

54

5856

542

5458

86

.8558.65

565

565

55898

786

8/95

5896

8656265

556478