Question

Find the 12th term from the end of the AP -2,-4,-6,...........-100.

Answer 1

AP= -100, -96, -92...............-2
n=12
a=-100
d=-96+100
   =4
Sn = n/2(2a+ (n-1)d)
     =12/2(2x-100 +(12-1)4)
     =6(-200+44)
     =6x-156
     =-936