Find The sum of the arithmetic sequences -10 ¼ , -10 ½ , -10 ¾ ………. -25 ½​

Question

Find The sum of the arithmetic sequences

-10 ¼ , -10 ½ , -10 ¾ ………. -25 ½​

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Lydia 3 months 2021-10-15T14:12:09+00:00 1 Answer 0 views 0

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    2021-10-15T14:13:25+00:00

    Step-by-step explanation:

    d=-1/4

    a=-10 1/4 or -41/4

    an = -102/4

    an = a+(n-1)d

    -102/4=-41/4 + (n-1)-1/4

    -61/4 * -4 = n-1

    61= n-1

    62 = n

    Sn = n/2(a+an)

    Sn = 62/2(-41/4 + -102/4)

    Sn = 31(-143/4)

    Sn = -4433/4 = -1108.25

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