Question

find the sum of -3, 1, 5...... to 17 terms

Answer 1

a=-3

n=17

d=t2-t1

1-(-3)

d =4

tn=?

t17=a+16d

=-3+(16*4)

=-3+64

t17=61

s17= n/2(a+tn)

=17/2*(-3+61)

s17= 493