Question

Find the sum of – 1676 + (-1669) + (-1662) + ... +(-115) + (-108).

Answer 1

Answer:

Step-by-step explanation:

This is arithmetic series

first term (a) = -1976

common difference = 2nd term - 1st term

                                = (-1669) - (-1676)

                              =(-1669) + 1676

                           d = 7

nth term = a + (n-1)d

(-1676)   + (n-1) 7 = (-108)

(-1676) + 7n - 7 = (-108)

-1683 + 7n = -108

7n = -108 + 1683

7n =   1575

n = 1575/7

n = 225

last term (l) = -108

sum = n/2(a + l)

$=\frac{225}{2}*[(-1676)+(-108)]\\\\=\frac{225}{2}*[-1784]\\\\=225*[-892]\\\\=[-200700]$