Question

Find sum of -3,2,7,12....,132
Arithmetic series

Answer 1

`a_1=-3 \\ d=2-(-3)=5 \\ a_n=132 \\ \\ a_n=a_1+d(n-1) \\ 132=-3+5(n-1) \\ 132=-3+5n-5 \\ 132=-8+5n \\ 140=5n \\ n=28 \\ \\ S_n=(n(a_1+a_n))/(2) \\ S_(28)=(28(-3+132))/(2)=(28 *129)/(2)=14 * 129=1806`

The sum is 1806.