Question

find the sum of these series. -15 + (-12.5) + (-10) + ... (50 terms)​

Answer 1

HERE YOU GO

Step-by-step explanation:

a = -15

n = 50

d = (-12.5) - (-15) = 3.5

formulae used:

a(underscore)n = a + (n-1)d

S(underscore)n = (n/2) * [a + a(underscore)n]

Solution-

• a50 = -15 + (50-1)3.5

       = -15 + 171.5

       = 156.5

• S(undersocre)50 = (50/2) * [-15 + 156.5]

                                     = 25 * 141.5

                       =3537.5

Sn = 3537.5

i hope it helps!!!

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