Find the sums given below :
(i) `7+10 1/2+14+...+84`
(ii) `34+32+30+...+10`
(iii) `-5+(-8)+(-11)+...+( -230)`

Explanation

(i) First term, a = 7


nth term, `a_n = 84`

common difference `d= a_2- a_1= 10 1/2 – 7= 21/2 – 7 = 7/2`


Let 84 be the nth term of this A.P., then as per the nth term formula,


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