Question

please solve question no 16

Answer 1

Hii..samayra....

Your question is about AP.....

Answer:

Step-by-step explanation:

a = 18

d = 15 (1/2) - 18

= 31/2 -18

= -5/2

t(n) = -49 (1/2)

a+(n-1)d= -99/2

18+(n-1)-5/2 = -99/2

(n-1)-5/2= -99/2 - 18

(n-1)-5/2= -135/2

(n-1)= -135/2 × -2/5

(n-1) = 27

n = 27+1

= 28

Now,

S (28) = n/2 [2a +(n-1)d]

= 28/2 [2×18 + 27×-5/2

= 14 [ 36 - 135/2]

= 14 [ (72-135)/2]

= 14 × -63/2

= 7 × -63

= -441

Hope it may help you!

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