Question 2 (iii)
Find the sums given below.
(iii) − 5 + (− 8) + (− 11) + ………… + (− 230)

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Solution

(iii) $(- 5) + (- 8) + (- 11) + \dots \dots + (- 230) F o r t h i s A . P, a = - 5 a_{n} = - 230 d = a_{2} - a_{1} = (- 8) - (- 5) = - 8 + 5 = - 3 L e t - 230 b e t h e n^{t h} t e r m o f t h i s A . P . a_{n} = a + (n - 1) d - 230 = - 5 + (n - 1) (- 3) - 225 = (n - 1) (- 3) (n - 1) = 75 n = 76 A n d, S_{n} = \frac{n}{2} (a + a_{n}) = \frac{76}{2} [(- 5) + (- 230)] = 38 (- 235) = - 8930$

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Similar questions

Find the sums given below

(i) 7 + + 14 + ………… + 84

(ii) 34 + 32 + 30 + ……….. + 10

(iii) − 5 + (− 8) + (− 11) + ………… + (− 230)

- 5 + (- 8) + (- 11) + . . . . . . + (- 230)

Find the sums given below:
(i) 7+ $\frac{21}{2}$ +14+...+84
(ii) 34+32+30+...+10
(iii) -5 + (-8) + (-11) + .... + (-230)

(- 5) + (- 8) + (- 11) + . . . . . + (- 230)

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