Question

Find the sum of 16 terms of an A.P: -1, -5, -9, _ _

Answer 1

Answer:

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Step-by-step explanation:

a= -1

d= a2-a1= - 5-(-1)= - 5+1 = - 4

Answer 2

Answer:

a = -1

d = -5+1 = -4

S16 = n/2 ( 2a + (n-1)d) = 8 ( 2×-1 + 15×-4)

= 8× (-2-60) = -496