WAEC - Mathematics (2012 - No. 5)
The nth term of a sequence is Tn = 5 + (n - 1)2. Evaluate T4 - T6
30
16
-16
-30
説明
T4 = 5 + (4 - 1)2; where n = 4
= 5 + (3)2 = 5 + 9
= 14
T = 5 + (6 - 1)2
where n = 6
= 5 + (5)2
= 5 + 25 = 30
T4 + T6 = 14 - 30
= -16
= 5 + (3)2 = 5 + 9
= 14
T = 5 + (6 - 1)2
where n = 6
= 5 + (5)2
= 5 + 25 = 30
T4 + T6 = 14 - 30
= -16