WAEC - Mathematics (1993 - No. 6)
The nth term of a sequence is given by (-1)\(^{n-2}\) x 2\(^{n-1}\). Find the sum of the second and third terms.
-2
1
2
6
12
คำอธิบาย
when n = 2
(-1)\(^{n-2}\) x 2\(^{n -1}\) = 2
When n = 3
(-1)\(^{n-2}\) x 2\(^{n - 1}\) = -4
Sum = 2 - 4 = - 2